Well it is a different type of mail system. I use it for catch all. I have like 200 domain names for various projects or registered to sell and I want to catch all emails sent to those domains without setting them up in mailcow. With Anonaddy I verify their DNS records and that's it. I can capture all emails sent to them and forward to a specific address. Also, I can use whatever email address I want with whatever domain I want to subscribe to services and keep track of who sells my email for instance. They also have a Chrome extension that you can use to generate emails, but imho that is overkill. Then if you see that one email gets too much spam you can simply delete that forwarder and it gets rejected in the future.
Well thanks to the soon to be dead /r/selfhosted on reddit I started selfhosting few years ago and now approximately 90% of my stuff is selfhosted:
as daily drivers and several others that I use from time to time.