It's against HN's rules to do promotional voting and/or commenting. We want voting and discussion to happen because people are randomly curious—not because they or a friend have something to promote. This is in both the guidelines (https://news.ycombinator.com/newsguidelines.html) and the FAQ (https://news.ycombinator.com/newsfaq.html).

However, there are different degrees of breaking this rule. For simplicity, I'll call them A and B. There are more than two of these categories, but let's keep it simple.

Degree A: OP is clueless about the culture and rules of HN. Out of enthusiasm, they tell their friends (or project community) "hey, I posted <link> to Hacker News". Friends are even more clueless but want to help OP so they come to HN and and create new accounts to upvote and post things like "Wow this is really cool! I think this is really cool! Woo hoo OP!!"

Degree B: OP knows perfectly well that HN doesn't allow voting rings or booster comments, but want some sweet sweet frontpage juice for their thing. So they organize and make a bunch of accounts (or co-ordinate a bunch of existing ones) to upvote and/or comment but also hide their tracks.

A is naive. B is abusive.

A is venial. B is cardinal. A = misdemeanor, B = felony.

A means well, but is hapless and obvious. B knows what they're doing and think they can get away with it.

A is the juvenile delinquent that responds to kindness and explanation. B is the hardened criminal that learns nothing but to game the system better next time.

B is an obvious ban. A, maybe not. If their work is good and they seem like they (and their friends) might become good community members with enough guidance, then they're welcome—even though the rules are the rules.

Going lenient on A would be a bad idea if HN were vulnerable to naive voting rings; but we've been writing software for many years to catch those. The A cases are so naive that after a few years we realized that we were better off going easy on them. They're not the abusers we need to worry about! and often they turn into good citizens.

If you really want to keep the login then maybe a message like we won't spam email you unless asked and only want your to log in to protect against bots would help.