As the title says is there a way to find all comments from a single user? If not I hope it becomes a feature in the future.

the only way i know of is to (programmatically) iterate through all comments, at
rule34.xxx/index.php?page=comment&s=list&pid=0
incrementing the pid until you reach the end (where the response is just "No comments")
and collecting all comments matching the user you're after

if you know when the user was created you can stop once you pass that date

That's a shame. I don't really want to go through every single comment on the site looking for one persons. Hopefully the site can get a feature for this sometime in the future.

well then it's an opportunity to learn how to write software

lol I'm here to fap not make software just to see some comments.