Ok, pros are psychologically you think it helps I suppose and obviously it's part of a sub-hobby of tennis. I'm not sure I trust most people to know what is best for their game though, I bet some here do, just not that many.
For the most part, it doesn't matter. If the process is objectively entertaining, or the end result is a racquet that feels slightly more enjoyable to hit with, then the end was worth the pursuit.
The people doing it for fun should pursue the angles that give them the most fun. And if that's customization, then so be it.
The people doing it for a living should pursue the angles that help them do that best. And (again) if that's customization, then so be it.
The reason most up and coming junior tournaments aren't as heavily customized isn't because customization isn't a useful tool to help many play their best tennis, necessarily. It's because to play your best tennis, typically, you want a racquet that feels and plays more or less like the ones you learned to play with. Talented juniors learned to play after polys and globally scaled economies drove the market toward lighter, more powerful frames. That doesn't necessarily mean they wouldn't do better with heavier, more flexible frames. Lots of high level pros are using polys with sledge hammers. But people stick to what they're comfortable with.
For older players, it's the reverse. Objectively, modern racquets feel nothing like older ones. And since old school, heavy, flexible racquets have proven at least as good at handling modern strings and strokes, it's hard to say it's not a win if you can make your 2021 tweener feel and play a little more like your 1995 relic, if that's what you're used to.
Let people enjoy the process. If it was just about picking the equipment that gave you the best results, most of these companies would go out of business and all the sub-5.0 duffers would be swinging 135 sq in Weed racquets out there. Not one person out of every thousand swinging a Prestige or a Pro Staff has any business doing so from a results oriented standpoint.