nitealso, valve have never once implemented a community balance change suggestion.
i agree with literally everything else you suggested (it's far better to identify the problem if you're a community member, not a propose a solution, designers have a ton of people that can shit out solutions and actually test them, it's identifying the problem that is the useful part, it's also half of what makes a good designer: capable of identifying the real problems (and making solutions that benefit the game the best).
but this statement is false. The eventual Blutsauger nerf (one of 4 versions in it), Medic regeneration change, Pistol ROF change, FaN nerf, original Sandman nerf and thrown Sandvich functionality/G.R.U. (irony) were all directly changed/added due to competitive community feedback with the TF2 Competitive Closed Beta back in 2009. They also listened and didn't add the PDQ (reworked it into the Gunslinger), didn't nerf the Ubersaw (they tried two different nerfs), didn't add the Fire Retardant Suit (eventually got reworked into Spy-cicle), and didn't add the Medigun with no overheal decay due to competitive community feedback in that same beta.
The Equalizer solely exists due to community feedback. They directly say this on the update page, they took the weapon idea from community members: http://www.teamfortress.com/soldierupdate/
granted, this was all ages ago (the only recent thing you could count is just features and valve listening to banny on not doing their proposed Reserve Shooter change he said would have been a buff, and listening to not doing something is technically just as important as listening to doing something) and was during a time when the high level 6s community had enough of valve's ear where they had an entire private branch of the game to play on and communicate with valve with, but there is precedence for it all the same.
(again, not that i think this kind of stuff in this thread is a very good way to go about any of it)