HTTP 3 has several compelling advantages over HTTP 1.1 and HTTP 2:
HTTP3 runs over QUIC, which natively supports roaming. This is especially useful for mobile clients.
HTTP3 supports native multiplexing, without the head-of-line blocking problem that HTTP2 suffers from.
HTTP3 allows congestion control to be implemented in userspace, which allows new algorithms (such as BBR) to be adopted before OS kernels get support for them.
HTTP 3 has several compelling advantages over HTTP 1.1 and HTTP 2: