Trends in extremes may result from systematic changes in amounts of variation and as systems regularize, their variation decreases.

From The Flamingo's Smile Reflection in Natural History by Stephen Jay Gould.  Despite his other shortcomings, he was such a gifted writer.  From Chapter 14, Losing the Edge.

I am a paleontologist by trade. We students of life’s history spend most of our time worrying about long-term trends. Has life become more complex through time? Do more species of animals live now than 200 million years ago? Several years ago, it occurred to me that we suffer from a subtle but powerful bias in our approach to explaining trends. Extremes fascinate us (the biggest, the smallest, the oldest), and we tend to concentrate on them alone, divorced from the systems that include them as unusual values. In explaining extremes, we abstract them from larger systems and assume that their trends arise for self-generated reasons: if the biggest become bigger through time, some powerful advantage must accompany increasing size.

But if we consider extremes as the limiting values of larger systems, a very different kind of explanation often applies. If the amount of variation within a system changes (for whatever reason), then extreme values may increase (if total variation grows) or decrease (if total variation declines) without any special reason rooted in the intrinsic character or meaning of the extreme values themselves. In other words, trends in extremes may result from systematic changes in amounts of variation. Reasons for changes in variation are often rather different from proposed (and often spurious) reasons for changes in extremes considered as independent from their systems.

Let me illustrate this unfamiliar concept with two examples from my own profession—one for increasing, the other for decreasing extreme values. First, an example of increasing extreme values properly interpreted as an expansion of variation: The largest mammalian brain sizes have increased steadily through time (the brainiest have gotten brainier). Many people infer from this fact that inexorable trends to increasing brain size affect most or all mammalian lineages. Not so. Within many groups of mammals, the most common brain size has not changed at all since the group became established. Variation among species has, however, increased—that is, the range of brain sizes has grown as species become more numerous and more diverse in their adaptations. If we focus only on extreme values, we see a general increase through time and assume some intrinsic and ineluctable value in growing braininess. If we consider variation, we see only an expansion in range through time (leading, of course, to larger extreme values), and we offer a different explanation based on the reasons for increased diversity.

Second, an example of decreasing extremes properly interpreted as declining variation: A characteristic pattern in the history of most marine invertebrates has been called “early experimentation and later standardization.” When a new body plan first arises, evolution seems to explore all manner of twists, turns, and variations. A few work well, but most don’t (see essay 16). Eventually, only a few survive. Echinoderms now come in five basic varieties (two kinds of starfish, sea urchins, sea cucumbers, and crinoids—an unfamiliar group, loosely resembling many-armed starfish on a stalk). But when echinoderms first evolved, they burst forth in an astonishing array of more than twenty basic groups, including some coiled like a spiral and others so bilaterally symmetrical that a few paleontologists have interpreted them as the ancestors of fish. Likewise, mollusks now exist as snails, clams, cephalopods (octopuses and their kin), and two or three other rare and unfamiliar groups. But they sported ten to fifteen other fundamental variations early in their history. This trend towards shaving and elimination of extremes is surely the more common in nature. When systems first arise, they probe all the limits of possibility. Many variations don’t work; the best solutions emerge, and variation diminishes. As systems regularize, their variation decreases.

Gould is using these observations to explain, by analogue, the disappearance of the .400 hitter in baseball.

It occurs to me though that his observation is a complement to my explanation of a different phenomenon.  It is notable today that in the American market for cars, there is far less variety of body style and performance attributes than at any time since 1900.  A four door sedan in 2024 is nearly identical whether produced by GM, Ford, Honda, Toyota, or whomever.

I have observed the standardization and have always attributed it to increasing regulatory pressures which lead to design conformity.  There are two specific areas of regulation in particular which lead to this - safety and fuel efficiency.

If you prioritize occupant safety, it directly leads to certain design requirements (got to have a roll bar).  If you prioritize fuel efficiency, it directly leads to certain body shapes (the engineering of aerodynamics).  The safety targets and the fuel targets drive all manufacturers into the same solutions.

And that is, I believe, a correct explanation as to why the richness of vehicle design has dwindled from exotic to plain Jane over a century.  

And while true, that is not incompatible with Gould's larger observation that "As systems regularize, their variation decreases."  

In the early nineteenth century, when the automotive industry was new, we had dozens, even hundreds of vehicle manufacturers.  From Automobile History.

Thirty American manufacturers produced 2,500 motor vehicles in 1899, and some 485 companies entered the business in the next decade. 

Hundreds of manufacturers, thousands of car designs.  There was dramatic variation in aesthetic, functionality, and reliability.  But as the industry consolidates and the commercial system reularized, variation decreased.

The system regularizing is intimately bound up in the regulation the industry.  It was not solely a matter of the needs of producers standardizing around the demands of the consumers, the demands of regulators did have their role as well in driving down the variation of design which could generate profit, meet customer demand, and satisfy regulatory requirements.

Regulation was important but it was also part of the larger process of a system of exotic and luxuriant growth followed by decreases in variation.