It's called trying. The computer fluent hackers will always get in easily, but the non-fluent ones will fail. It's a safeguard such as many software makers safeguard their products even though torrent suppliers can easily break them. The majority (the non-fluent computer users) will not breach this safeguard, I guarantee you. 75 is actually a low number compared to the amount of cot players. However, I do agree that WC3 is fail for not including a unique identifier to each cdkey so you can actually ban the cdkey the person is using like many games do such as UT2k4. BNet/Blizzard only cares about themselves and that they can permaban and not individual hosters. This question is the same as asking why try banning maphackers. Oh but they tried, and they succeeded. The % of maphackers now is much lower than it was a year ago. I know from ladder and a lot of competitive team maps and I can tell the % is lower through experience.
Btw, do not post a link like that ever again. Bots should be able to decipher spoofers, it seems the latest version of bot has different spoofcheck settings and letting spoofers in...I'll look into that.