Guys, it's not that complicated.
I teach tennis at an academy and have been weighting and matching racquets for the players with the usage of an RDC. The difference a properly weighted racquet makes for a top junior player is immediate and pretty amazing. Depth, directional control, and ability to play offense are impacted right away.
It comes down to this:
Elite pros must customize their racquets to compete at the highest level. There are pros that don't know any better playing around the 1000s (former college players, Operation Liftoff Alex Donski). They are LIMITED by the racquet they use. I've played tennis long enough to see the difference--former division 1 player. Swingweight is the most important factor, and it must must must be at least 335+. Stock racquets are 320s.
The pros do this by getting an MRT, an outside company like Ring Roll or P1, or a representative from their racquet company (i.e. Wilson Pro Room), to add weight under the bumper and in the handle.
It doesn't matter how incredibly fit, or strong, or how good your hand eye coordination is. Stock racquets cap off your level of play at a certain level--for many academy players, that means a big college. The insane talents can make it to around the 1000s with stock racquets. It's simply too difficult to play higher than that level with a stock racquet.
Stock racquets are made with the average consumer in mind and perform as such.