HTTP1.1 is expected to just work it has been here for a very long time. It takes time to understand, support and adopt new technology. I'm not sure if the blame should be on HTTP2 in this case.
Regardless of who the blame should land on — I don't have a strongly held opinion about that — the point remains that HTTP1.1 is a super old, well understood, relatively simple protocol that everyone has done correctly for years. In comparison, HTTP2 is the new, more complex thing and it's understandable there are growing pains and incompatibilities. I just don't want to debug those issues in something that worked great for me on HTTP1.1.