Couple of years ago I was able to change all posts I ever made in one go. It may have been a tool somebody made, I’ve forgotten already. “Fuck spez” or something clever like that.
Don't, for now that only helps reddit gaining traffic. I had on several occasions the need of reddit and had to go to multiple posts because the information I needed was deleted, and I doubt I'm the only one experiencing that. Lemmy is great, but it's still a far way of what reddit hass accumulated over the years, and it also doesn't really show up in search results yet.
No easy way now, I guess. I did all of mine just before they shut off API access which allowed me to edit every comment to a brief explanation of why I was leaving, and then deleted them all. But that wouldn't work anymore with the API access.
I get the sentiment, and everyone is free to do what they like.
But reddit is still a source of information. I don't intentionally or regularly go there anymore, but sometimes when trying to find an answer to something it will pop up. And a few times recently the person that gave the answer nuked all their comments. It's pretty frustrating.
Personally I think deleting the account is enough if you think you even MIGHT have some useful comments around. I don't think old comments are contributing to keeping people on reddit, but it does help people who just need some quick info.