the problem is the difference between skill and bot's.
lot of players cry "HAAAAXX" because they get owned many times by a good skilled player.
there must be an evidence, to ban an obvious cheater. but what is a good evidence?
when you see a guy swiching his gun unreal between his opponents. its 99% a bot. but even not evey time. lags produce sometimes really strange situations... and what about wallhacks? "huh, this guy always see me first, goddammit..." in a figt is it such a big advance, when you see your opponent, before he does. and yea, you cant see his wallhack, if he use any.
the anti-cheat tools need the codes of the hacks, to ban guys wich use them. but its expensive to buy them all, and anyway bad to support the cheat-programmers, by buying their cheats
i think, nobody should underrate the problem, wich cheaters bring.