Too many TCP connections is a browser limitation (for DDOS prevention reasons mostly). Inside each connection you are limited by head of line blocking, either b

Too many TCP connections is a browser limitation (for DDOS prevention reasons mostly). Inside each connection you are limited by head of line blocking, either by HTTP/1.1 itself or by TCP when using HTTP/2. You are correct that HTTP/3 can stream multiple resources over one QUIC connection via multiple channels and each channel can make progress independently from each other channel. Nowadays (assuming a modern browser in a non-udp restricted environment), you can just download hundreds of resources at the same time from the same server through one HTTP/3 connection without much overhead and transport level limitations.