I understand the sentiment, and everyone of course has the right to do this with the content they posted, but please consider:

The only thing this probably achieves is fucking over people googling for specific information in the future. How often have I searched for some really specific problem or information, only to find a thread in some niche subreddit from years ago with exactly what I needed?

For Reddit itself it's trivial to keep previous versions of comments. Also deleted posts can just be flagged as 'hidden' and still remain in the database. They already have your content and won't be giving it up. So please consider leaving it available for the public as well.