[Spivak]

Being cagey about the reasons for bans is

1. To keep people from cozying up to the electric fence. If you don't know where the fence is you'll probably not risk a shock trying to find it. There are other ways one can accomplish this like bringing the banhammer down on everyone near the fence every so often very publicly but point 2 kinda makes that suck.

2. To not make every single ban a dog and pony show when it's circulated around the blogspam sites.

I'm not gonna pass judgement as to whether it's a good thing or not but it's not at all surprising that companies plead the 5th in the court of public opinion.

[bink]

Sorta related to (1) but not really: there are also more "advanced" detection techniques that most sites use to identify things like ban evasion and harassment using multiple accounts. If they say "we identified that you are the same person using this other account and have reason to believe you've created this new account solely to evade that ban" then people will start to learn what techniques are being used to identify multiple accounts and get better at evading detection.