A fielding restriction written to encourage attacking play ended up dictating an entire generation of top order selection.
Two fielders outside the circle decided who opens
Rules pick players. Not directly, and not by intention, but as surely as any selector. The clearest example in white ball cricket is the powerplay restriction, and specifically the number of fielders allowed outside the ring during it.
With only two men back, the geometry of the field is simply different. Gaps that would be covered later in the innings are open, the risk of a mistimed aerial shot is lower because there are fewer bodies in the deep, and the value of hitting over the top rises sharply against the value of finding gaps along the ground. A batter who can clear the infield for six overs is worth a great deal. A batter whose method is timing, placement and running is worth much less than he would have been under a different restriction.
So selection followed. Openers stopped being technicians who saw off the new ball and became strikers with a ceiling. Domestic systems reorganised themselves to produce that player, because that is the player who gets picked, and now there is a shortage of the other kind in almost every country. When a pitch does something in the first six overs, and a side actually needs somebody who can leave the ball and bat time, a lot of teams find they no longer employ one.
I think this is a real cost and it is worth naming as one, rather than treating the aggressive top order as pure progress. The format is more entertaining. The skill base is narrower. Both things are true.
The interesting counter comes from the middle overs restriction, which allows more fielders out and quietly rewards a different skill entirely, the ability to score at a run a ball without boundaries against a spread field. That skill is undervalued because it produces unimpressive strike rates in a phase nobody analyses closely. Teams have started noticing. Not enough of them.
If administrators wanted a different game they could get it with one line of regulation. Three fielders out in the powerplay and the premium shifts immediately back towards placement and running, and within four years the academies would be producing a different batter.
Whether that game would be better is a matter of taste. That the rule, not the talent pool, is doing the choosing seems to me not to be.

