That isn't necessarily an argument for throwing weapons being broken in damage/accuracy.
Aside from the in-depth experience and knowledge high level players have, they are also uniquely biased against throwables (and archery). The vast majority of this player group's preferred playstyle is (unshielded) melee combat, as that's where the highest skillcap in the game resides. Now what's the one thing that will thwart all that fancy swordmanship, no matter how good you are? If a worse player wields a melee weapon, there's little chance he'll beat you, but if he wields something ranged, that chance increases exponentially. The worse ranged weaponry is however, the less that chance becomes once more. It's an equalizer between high and low level players. Somewhat levelling the playing field between new and experienced players is more beneficial than it might seem.
Indulge me and compare the viability of ranged weaponry at its two most theoretical extremes:
- If ranged weaponry was overpowered beyond compare then the melee skillcap would become redundant. It'd still be there technically, but it would rarely if ever come into play. You'd have a really tough time differentiating high level M&B players from lower ones on the scoreboard. Right now that's not the case. Even if I'm utterly wrong about this topic and throwing weapons are insanely broken (in terms of damage/accuracy) as you say, a high level M&B player will still easily top any scoreboard. The disparity with lower level players will be greater than if throwables were nerfed in damage or accuracy, true, but as long as the disparity is significant I don't see a problem.
- If ranged weaponry didn't exist or was nerfed to the point that it might as well not exist, then the melee skillcap would become all-encompassing. The skill floor would soar and the accessibility of the game would plummet. It'll be a cold day in hell if a new player defeats someone at a higher skill level. Becoming truly good at M&B melee combat isn't something that happens overnight, it takes a lot of practice. Influx of new players would come to a grinding halt as nobody enjoys getting decimated with nothing to fall back on while they get better. In Bannerlord, as back in Warband, you see a lot of inexperienced players playing an archer class, that's no coincidence.
I believe throwables currently occupy a very balanced middle ground between those two extremes.. They can occasionally allow you to get the better of a higher level player, but in the end that higher level player will still come out on top. I do still very much agree with you though that their availability should be reduced, no need for just about every class to have access to them.