You're saying 128 would disadvantage player's lower than 128 fps right. At the same time, 64 tick disadvantages everyone, no matter what their fps.
The amount of bullet's that fail to register on 64 tick servers is utterly ridiculous, being "CS:GO'd" should not be a thing because of the garbage servers.
Also as I said, it's not up to valve to worry about people's PC specs, CS is certainly on the easy to run side of games. What it is up to valve to worry about is bullet's registering in competitive games aka get better servers. Fix the hit boxes that always seem to be broken and fix the anti cheat.
Showing me stats of how many bans Vac is doing doesn't prove anything. There are games other than CS that use VAC, and it does indicate how many cheaters it misses (which would be a lot more). Also I believe VAC and VACnet are different. VACnet is their "ai" of detecting cheats from player's but "cheater's" also need to be reviewed, they don't let it ban players.