I think multiple accounts for one person should not be banned, and am willing to communicate amicably with users who don't agree.
Multiple accounts for one person won't break the rating system. As some people register alt accounts and achieve high ratings in a short time, it may seem that other people are facing more difficulties when trying to increase their ratings. However, some users also give up their old account and register a new one when their ratings drop below 1500, which balances the influence. As long as users don't participate in a single round with multiple accounts, it's not a big deal.
It's not a big deal that alt accounts might show up in Div.2 winner lists. In fact, Div.2 only score boards doesn't mean much. The winners are not extremely well, but just lucky for having their ratings just below 2100. A beginner will likely become a master before reaching the top of Div.2. If a skilled user registered a codeforces account for the first time, he(or she) will be also likely to show up in the winner's list of a Div.2 contest. We can't assume all the new users of codeforces as similar levels.
It's not a big deal that alt accounts might show up in Div.1 winner lists. If they have enough skill, no matter which account they are using, they will achieve good ranks in Div.1 contests. So what's the matter?
Multiple accounts for one person does violate the terms of agreements, but the terms of agreements aren't fixed. It can be edited from time to time to satisfy the needs of the codeforces community. Now I'm appealing to change it.
We need some privacy here. Some participants are so famous that no matter what they post, the whole country (possibly the whole world) will know it. Allowing users to register alt accounts and hide their identity, a bit more privacy in the cyber space won't do much harm. Some malicious to abuse alt accounts and post offensive contents, but it is posting offensive contents, instead of creating alt accounts, that should be punished. We can come up with other ways to stop offensive posts, for example, hide posts by users with too negative contribution might work.
My English is not very well, so please forgive me if I'm not behaving politely.
Any comment is sincerely appreciated.