Its certainly possible to nuke an account, but Staff does not do it on request. I dont know why, but I can think of several reasons. E.g. someone that gained access to the account could request a nuke etc.

The way I do it for SAD (someone else linked it above) is that I start with the oldest posts and delete every post by hand. I also read each post to make sure (as beast as possible) that said post is not related to any scams and can safely be deleted. Everyone can - of course - just do this themselves, its just tedious and take a very long time. ~100 posts per hour is a reasonable speed.