Which is why this thread exists, so that it can possibly be implemented into DA.
Opening the zone file in emacs and then making it immutable serves as a fine makeshift solution. I could see an argument for individual zones for each subdomain if there are a fair amount of records per subdomain. When there's a lone MX record however, I don't see the benefits of the setup outweighing the effort necessary to create all of the zones and tying every single one into our system. The last part could be left out but then the user would be unable to make changes themselves and you're back to square one in terms of supporting it.
Opening the zone file in emacs and then making it immutable serves as a fine makeshift solution. I could see an argument for individual zones for each subdomain if there are a fair amount of records per subdomain. When there's a lone MX record however, I don't see the benefits of the setup outweighing the effort necessary to create all of the zones and tying every single one into our system. The last part could be left out but then the user would be unable to make changes themselves and you're back to square one in terms of supporting it.