This has been the approach for a long time. Here's me saying the same thing 4 years ago: https://news.ycombinator.com/item?id=11543284. The main thing that has changed since then is that we now have the ability to rename accounts. When people want to delete their accounts, a combination of randomizing the username and/or deleting some posts and/or redacting sensitive information has proved able to satisfy nearly everybody.
I suspect that you'll be addressing the same question over and over as time passes. It won't go away.
Addressing the same questions over and over is much, if not most, of my job. In recent months I've started to link more systematically to past explanations, since the sequences of questions on many topics have started to converge. I intend to compile these into either a v2 FAQ or a series of short essays about moderation topics, or something, which in the future can simply be linked to. The question of account deletion will certainly be in there.