Caps are queues, and queues are the worst allocation system ever invented! Price it instead — congestion fees that float with demand, revenue ring-fenced for residents. Venice had the right instinct. You don't need a wall, you need a meter.

Sorry for my English. Capacity is not an opinion, it is physics. The sewage system, the water supply, the ambulance access — they were designed for a number. You cannot price your way past a pipe. When demand exceeds the pipe, the meter does not protect you. The limit does.