Most of that knowledge was only deleted but not saved in any other way […]

That was perhaps the saddest part about leaving Reddit. I also opted for the edit-and-delete approach, because I didn't want Reddit to use my posts to train LLMs. But man. Years of trying to be helpful, sometimes really going out of my way to address something properly; gone.

But honestly, I don't know of any alternative. Even if I archived everything, it wouldn't be as accessible to anyone as it used to be on Reddit.

Reddit had (and imo still has) a monopoly on searchable advice from strangers. There's a reason they wanted Reddits data to train LLMs.