Less that and more the combination of bad tools, labyrinthine “standards” which were usually poorly implemented by said tools, and lack of concrete use-cases. Almost nobody had a case where implementing it showed a clear business value so most of the “you should do this” advocacy was along the lines of “this will become useful later” and that was a hard sell because it took many years before you could go to a webpage, read some decent instructions, mark something up, and run it through a validator or another client and get the expected data back out.