I comment on some blogs where I just need to enter an username, optionally my mail address and no account creation required at all. I don’t know how those blog

I comment on some blogs where I just need to enter an username, optionally my mail address and no account creation required at all. I don’t know how those blogs manage spam but there is just none. So it’s totally doable. An option I see is to just store a random token in a cookie and require pre-publish moderation for the first n posts from this token. Your regular commenters are probably just using the same 1 or 2 devices to read your blog.