checking if the server has sv_pure 2 is done in a matter of seconds, never checked myself what it looks like for sv_pure 1, if the allowed stuff gets listed.

[...] Are you sure? That's wayyyyyyyyyyyyyyyyyy outside the area portal for badlands spawn.

[...] CC's dont pick up on sounds unless they're pretty near. For example, on gullywash I could be in spawn on last and hear a medic uber on mid (if nothing else is going on), but the CC won't pick up on that. tl;dr cc is rather useless

[...] Well, I don't see any big problem in sv_pure 1 and whitelist. This may be done in the next config release to minimise reconfiguration. The only sounds I ask for are your_team_lost, your_team_won, your_team_stalemate, tf_dominate, tf_revenge, tf_nemesis. These sounds would give no unfair advantage to anybody. And those who don't use custom sounds won't see any difference either.

Firstly, as you said, allowing custom sounds means servers need to be on sv_pure 1 with an appropriate whitelist. This is inconvenient. There's enough things people have to worry about on their server already (Configs, item whitelist). The less configuration needed, the better. There are plenty of occasions where the configs are missing/not executed properly/whitelist incorrect/etc already. Secondly, you can probably get an unfair advantage when you can mod your sounds. For example: amplify the medic's "uber ready" call so it really stands out. Or doing the same with the spy decloak sound (I personally never hear it when it gets a bit hectic.)

[...] CC's dont pick up on sounds unless they're pretty near. For example, on gullywash I could be in spawn on last and hear a medic uber on mid (if nothing else is going on), but the CC won't pick up on that. tl;dr cc is rather useless

The distance on when a sound counts as audible is quite astounding and bordering on the unhearable when you have calls going on, exactly why CC is useful to some people (to me it just presents useless and beyond obvious info)

[...] Don't close captions only appear if you can hear the sound anyway? Or should be able to hear it.

[...] To be fair, the same effect can be achieved with closed captions (which are not limited by sv_pure).

Secondly, you can probably get an unfair advantage when you can mod your sounds. For example: amplify the medic's "uber ready" call so it really stands out. Or doing the same with the spy decloak sound (I personally never hear it when it gets a bit hectic.)