Summary

The global mob cap, while adequate for a singleplayer world, is limiting when it comes to running community BDS servers.

Steps to reproduce...

1. Start a BDS server
2. Have a number of players online and creating pens of chickens, cows etc
3. Note that as players make bases for themselves, mob spawns reduce significantly

What I expected to happen...

Larger servers should be possible without mob spawns being crippled

What actually happened...

On a server with 10 people, that averages about 20 mobs per player, a small base with only a few animals in pens will consume a good portion of that cap. It leaves larger servers devoid of hostile spawns.

Notes...

• On Java the global cap scales with the number of loaded chunks. This means the more players online, the higher the cap.
• While mob farms (eg chicken cookers) with tens/hundreds of mobs could be considered overkill they are also part of the sandbox. With no indication you've gone over this invisible cap many don't understand why nothing is spawning for them.
• On larger servers there's very little admins can do to prevent hitting the cap. Just general play by everyone online, without massive farms, will fill the cap.