I know this is a necro bump. But... others may see it from google searches.
Thanks for the answer! I don't really understand how this can be used if I "own" tho whole second level domain, but I will try and google a bit more with that keywords.
Don't think the abuse in question is much about people attacking someone else's domains, but rather people using their own domains with the intent of abuse. For example phishing scams could dynamically respond to hundreds of different possible aliases, with a legit looking domain in the front of the alias.
Sad, that some people abusing this take a usefull feature away from all people
They didn't remove the feature, they just put the feature into the hands of the DNS admins, which you'll need to email email@example.com
in order to request it's addition or modification.