IIRC it was present in that version, don't quote me on that.
Also why disable? Is it a challenge server?
Leaving exploits like that can cause a server to become dead quite quickly.
Players are quite habitual and play in seasons by the looks of it. When a new modpack/ world comes around they will do all the things until they run out of the things and never log in till some new stuff shows up. If an exploit makes those things faster or makes content pointless to do they don't stick around as long.
Sure plugging up exploits with bans/ removals can drive players away but chances are they are not players you want around anyway. It sounds elitist but if you are forking out the big bucks for a server then it's your way or the highway. If a server owner want to plug up an exploit then that's how you have to play if you want in their server.
When it comes to server numbers there are 2 factor to consider, recruitment and retention. Ban the wrong things and both will hurt, but not banning things that need it will create a bleed of really bored players. Keeping players interested is tricky business that requires a keen sense of balance.