LOL you were saying?
Maybe now thats true, but in 2019 when classic launched, the servers were less layered and had a MUCH smaller maximum capacity. If only 10,000 people can be logged on simultaniously, then at peak times, medium pop servers can have queues. You can 100% have a medium pop server with queues.
As i said this WAS true in 2019, but blizz has since drastically increased layering and population caps, since thats what the people want. They want super servers. If absolutely every single person who plays on a given server tries to log in, there will be queues. Maximum concurrent capacity =/= total number of active players
If there are two islands, 1 with 10,000 ppl and 1 with 500 people and everyone on both islands are trying to get into a building(on each island) that holds 400 ppl, then people will be waiting on both islands.