SSE was first built into a web browser back in 2006. By 2011, it was supported in all major browsers except IE. SSE is really just an enhanced, more efficient version of long polling, which I believe was possible much earlier.
Websocket support was added by all major browsers (including IE) between 2010 and 2012.
Im old enough to have worked with asn.1 and its various proprietary “improvements” as well as SOAP/wsdl and compared to that working with protobuf/stubby (internal google predecessor to grpc) was the best thing since sliced bread
Even in 2025 grpc is still awful for streaming to browsers. I was doing Browser streaming via a variety of different methods back in 2006, and it wasn't like we were the only ones doing it back then.
and also canonical content streaming was in grpc. in http there was no common accepted solution at old times.