We used to have mobs enabled on creative at one time. I believe this was a glitch or a bug but they were enabled. It was then proven that if you enable/allow mobs on Creative that people will spawn tons of them and cause lag due to the massive entity count. I had to deal with at least 2 situations with mobs on creative that were a hassle: The first instance was wen someone spawned a ton of guardians and then put invisible potions on all of them, this meant I couldn't see any of them and had to try to kill these rapidly bouncing guardians, took me around 45 minutes to finally kill them all through killing with instant damage potions, my sword and now. The second instance was when someone decided to spawn in a ton of blazes which were flying everywhere. I do not agree with entities being enabled/allowed but maybe certain members/ranks can have perms to use spawn eggs?
I remember the guardians issue. I was online trying to help at that time. Regarding certain ranks being able to use spawn eggs, even donors could cause mischief with this perk. So you never know if it's a good idea or not.
Add it so you have to pay a certain amount to spawn or only a max of 1-10 per chunk or plot. And they can't leave your plot or they get killed.