GDPR has exceptions, this would be such an exception that doesn't allow you to simply invoke GDPR and get everything deleted. They just have to anonymize the poster by deleting their signature, avatar, profile,... while the posts can stay intact (unless they contain personal info).
Do you think they are going to go through each of your comments individually to determine if it contains personal info or not? That requires actual time and effort, and as an individual user you or your comments are nowhere even remotely in the vicinity of important enough for that.
It’s far easier for them to take the loss and delete wholesale.
Do they do this? I don’t know, I haven’t done it. But it certainly could be argued that by them not doing this, they are not fully complying with the requirements of a GDPR deletion request.
That would destroy their whole value proposition, your user generated content is their goldmine. Of course they don't have to sift through your thousands of posts to find the one that has GDPR info, you'll have to show them the post.
You cannot impose requirements like that as part of the deletion process.
It is 100% not the user’s responsibility to keep track of this information. That is explicitly a requirement of the provider and it is fully on them to ensure that a deletion request deletes all the personal data. If they didn’t tag it properly and can’t ensure that, then that is their problem to solve not yours.
Their value proposition is also not a single user’s data. It’s the entirety of the data set. One user’s data is nearly worthless, certainly not worth enough to have a human review it. Which was my point.
That does assume that reddit actually updates the comment entry in their backend instead of keeping histories of the edits which I'm not sure we've had any insight into.
That’s my assumption too, keeping a history for every user increases complexity tenfold, while flagging deleted comments seems to be a common practice even in smaller companies because it’s so simple.
Another user said they tried the data dump GDPR request and the comments included deleted comments but only the edited version, so I guess this can be verified at least.
That could have changed, sure, but nothing indicates that is the case.
You could also go the GDPR route and request all your data be deleted, if you are subject to that. They would be forced to comply with that request.