i bet they do now, but i've checked back now and then, and all of my comments and posts are most assuredly gone.

edit: i've gone back to check some old haunts, place i know i've commented, and i did some seaching with google using my old usernames, as google uses its cache to match to the posts\comments, even though they're not there any more.

i see old posts that are graveyards of deleted comments, some with simply deleted accounts, and many others where both the account and comment are deleted. i don't see any gibberish comments. the ones i know are mine (because replies quote the comment above, which i recognize as mine), are all just deleted in their entirety, so it seems they didn't do comment versioning, at least not past the first edit. i see no posts under any former username of mine.

the efforts to scrub my content from reddit last May appears to have worked. sadly, since the API lockdown, those tools no longer work.

Reddit used to be open source and the source is still on github as a read only archive.

AFAIK back then edit history was only kept briefly. Enough to roll back an accidental edit (if you have admin privileges anyway) but not far enough back to view old versions of posts.

Of course, they would have backups, and maybe the code has changed, but I wouldn't be surprised if it hasn't changed and those backups are impractical (slow/expensive) to access.

Keeping old revisions is a common practice but it's also expensive and in reddit's case totally unnecessary.

you can request your reddit data, and they provide every comment along with edits as far as I remember, it was uncomfortable but i'd never posted anything regrettable at least

imagine getting your hands on u/spez's reddit data