The problem with cheating in TF2 is never going to stop (or even slow down) unless Valve can find a way for alt accounts to not be as effective as they are right now to the cheaters themselves:
The general consensus when it come to that point is having an hour limit for competitive, say 100-200 hours. Even though hackers could easily AFK for those hours, it would act as a similar deterrent of having to buy CSGO on a new alt for $20; However in this case it would be wasting their time, not their money. It wouldn't remove hackers from casual either, but I feel getting them out of comp is the primary concern here. In addition, do remember that the hour count could be based on your hours in-game on casual or certain community servers only, as it's common knowledge that those stats are tracked at this point. With restrictions like that, AFKing all those hours would be even more annoying, as any server where the hours actually counted would auto kick them after less than 5 minutes of AFK time. Alongside the need to get a new phone number every time (alongside new IP/ HWID masks if those kinds are bans are eventually implemented), comp could lose a majority of its cheaters, presumably leaving the dedicated few behind, as it is with most other games nowadays.
This also relates to how many new players barely know how to play the game properly, which is especially problematic in comp; This time limit would open up doors for newer players to train a bit in casual/ certain community servers first, which would smooth the "skill bell curve" a bit, and let more players get into competitive without getting totally steamrolled/ yelled at.
And don't even get me started on how this would help out community servers, too; The possibilities for a "official whitelist" with a per region sorter are endless, especially if the above changes came into effect.
Tl:Dr It's not about banning people outright, it's about deterring them in the first place, as in principle any system can be broken no matter how good it is. And at the same time [in this particular situation], you could kill two birds with one stone, you could use the "deterrent system" as an aid for newer players to improve on official Valve/ community servers alike. Sounds pretty good to me.