Not personally onboard with this. I think we all know that Reddit is nothing without its users and the content they put out, it is also a good source for people finding information online. I can't count how many times I have googled something with "reddit" behind the query, so I don't believe people deleting past content before taking down their account will be "making the internet better", and replacing it with gibberish is even worse. I get the intent behind it, just not onboard with it.
IMO, if you don't support Reddit, just don't use it. Don't make any comments nor any new posts. I support subreddits going into restricted mode where posts still can be viewed, but no new content can be added.