A cell phone is not a router. You have to receive the packets, rewrite them (because it is a NAT) and send them on. WIFI is also a shared network, you have to negotiate clear air because it can't handle collisions.'
Routers optimize things, but they still use memory. 150 users is ludicrous, maybe it has the ability to handle that many connections but that must be theoretical. I run some enterprise wfi APs, and we try and get < 15 users per AP for office area. A conference, we can handle 100 per AP. But that isn't full throttle, like streaming video. Probably web browsing/mail service at most.