But if you start tracking accounts by IP, then you could IP ban so that people couldn't create alts to escape moderation.

In many cases it'd be really terrible for our moderators. Since you're only allowed one account-- unless you're given permission to make another and follow a few additional guidelines-- we'd very likely see people deleting accounts to evade moderation history. In cases like that we'd lose logs of someone's past history on the site and have to treat them as a new user when they came back on a new account since we'd have no proof they'd been here before.

If it's a privacy issue and you're having problems with someone using your profile or information on it to stalk, doxx, black-mail, or otherwise harm you then there's other ways for us to help you than deleting an account. We can lock an account so your profile can't be directly viewed, purge widgets on your profile, or edit forum posts containing things like your full name/home address/e-mail address.