Moreover, we have gone from Microsoft pushing complexities to Google.
Like the latest two HTTP protocols are both based of tech that google has already made. However, IETF is like that sounds good. It's got it's advantages, but there is very little push back saying well that makes things more complicated.
For instance with HTTP/2 it has support for pushing files to the client. Most back end web stacks are still trying to think of good ways to make that easy to use. Mainly since what files to send depend on what the page contains. So either you have to specify a custom list or the web-server now needs to understand HTML to get a list of required resources. This also gets more complicated since a push will be useless if the resource is already cached. This means your webserver has to have some kinda of awareness of how clients will cache data. Again this starts to mean your web server needs more client knowledge.
This is does not even take into account how the browser should handle these things.
Additionally, while cryptography is a good thing, the standard for HTTP/2 does not require it. However, pretty much all the browsers ignore that un-encrypted HTTP/2 is allowed. So if you wanted to run HTTP/2 without TLS the browsers act like site does not exist. This gets into the problem since there are so few browsers they can basically make defacto standards. So if you went through the effort and followed the standards what you encounter may not follow those standards at all.
The standard for h2 may not have required it, but practically it was required. There are middleboxes on the internet that assume any traffic over port 80 is http 1.1, and will destroy/interfere/break non-1.1 traffic. There are also servers that will respond with a 400 error if they see an unrecognized protocol in the upgrade header. This is why actual data shows h2 has a higher success rate when sent over tls.
IIRC MS/IE wanted to implement it, but they backed off because of these issues
Asking browsers to implement h2c is asking them to make their browsers flakier... their users would see a higher connection error rate... which the user WOULD attribute to their browser, especially if they open the same URL in another browser without h2c and it works.
Using the upgrade header instead of alpn is slower anyway.
Like the latest two HTTP protocols are both based of tech that google has already made. However, IETF is like that sounds good. It's got it's advantages, but there is very little push back saying well that makes things more complicated.
For instance with HTTP/2 it has support for pushing files to the client. Most back end web stacks are still trying to think of good ways to make that easy to use. Mainly since what files to send depend on what the page contains. So either you have to specify a custom list or the web-server now needs to understand HTML to get a list of required resources. This also gets more complicated since a push will be useless if the resource is already cached. This means your webserver has to have some kinda of awareness of how clients will cache data. Again this starts to mean your web server needs more client knowledge.
This is does not even take into account how the browser should handle these things.
Additionally, while cryptography is a good thing, the standard for HTTP/2 does not require it. However, pretty much all the browsers ignore that un-encrypted HTTP/2 is allowed. So if you wanted to run HTTP/2 without TLS the browsers act like site does not exist. This gets into the problem since there are so few browsers they can basically make defacto standards. So if you went through the effort and followed the standards what you encounter may not follow those standards at all.