Yes and no. You're right that there's no button you can push to delete an entire account history, but wrong that there's no way to remove HN comments. We take care of deletion requests for people every day. We don't want anyone to get in trouble from anything they posted to HN, there's nearly always something we can do, and we don't send people away empty-handed. I can only think of one or two cases where we weren't able to make a user happy, and neither of those cases had to do with identifying information being left up on the site.
The reason we don't delete entire account histories wholesale is that it would gut the threads that the account had participated in, which is not fair to the users who replied, nor to readers who are trying to follow discussion. There are unfortunately a lot of ways to abuse deletion as well. Our goal is to find a good balance between the competing concerns, which definitely includes users' needs to be protected from their past posts on the site. I don't want anyone to have the impression that we don't care about that; we spend many hours on it.
I get the reasoning, but I don't see this applied to some platforms. Reddit and Discord allow you to both delete and edit older comments, and there's no limits on how far back you can go (so you can, if you wanted, edit or delete your entire history).
Under the GDPR a subject is allowed full erasure rights. If I say I want you to delete my content from x date to y date, or a particular post, or everything entirely then that shouldn't be an issue. A request may be bothersome, but that's what happens when you don't offer that functionality natively.
I noticed a few days back you didn't like it when a user made a new account, except with the internet these days and how everything is archived for all time, throwaway's are the only option. Building a comment history is extremely dangerous, especially when you might forget what details you may have posted or how meta-data can leak through (such as what subs you post in, any details you posted that could identify you etc).
You can't have it both ways: no to multiple accounts and also no to control over your data. I might have 50 accounts, dislike it? Give me proper control over my comments. (to be honest, it may just be worth making a new account for every comment for maximum privacy, it's extreme, but it's a viable option).
If I want to delete them, that's my choice to freely make. Your thoughts or concerns are not relevant to me, thankfully, the GDPR agrees.
I noticed a few days back you didn't like it when a user made a new account
I think you must have misunderstood whatever the moderation comment was, there's no prohibition on throwaway or multiple accounts. Just against using them to violate the site guidelines which is a different thing.
The reason we don't delete entire account histories wholesale is that it would gut the threads that the account had participated in, which is not fair to the users who replied, nor to readers who are trying to follow discussion. There are unfortunately a lot of ways to abuse deletion as well. Our goal is to find a good balance between the competing concerns, which definitely includes users' needs to be protected from their past posts on the site. I don't want anyone to have the impression that we don't care about that; we spend many hours on it.