> Reddit suspends accounts en mass, and when they do they nuke their entire history of comments on the site.

That's not quite true, if an account is permanently suspended, the user page is unavailable for viewing, but the comments still remain in their respective threads.

It's only if an account is shadowbanned site-wide that all the comments are automatically removed too. This is intended only for spammer accounts, but can hit genuine users who are both newly created and end up being downvoted below a certain threshold.