And yet AMD has never managed to make a meanigful impact whith any of those architectures. In fact the last time they ( before ATI was bought by AMD) really managed to pull the rug under Nvidia was the R300 series ( R9500,R9700,R9800 ). And that came out 20 years ago.
Back in 2006 when AMD purchased ATI, it has proven to be too much to chew for AMD. The aquistion itself nearly bankrupted AMD, RnD was cut quite significantly on both CPU and GPU segments. It took AMD almost another 15 years come back from that.
In the end AMD does make the best APUs on the market, but when it comes to discreet GPUs they're just good enough.
As for lack of support for AMD features, there's a simple reason for it. Lackluster developer support. As developer reaching out to AMD for support you get ping ponged between departments and spend days on something that should have taken hours to resolved. For all shenigans Nvidia pulled at us over the years, they have this area covered rather well.