There are always format fanboys but it really wasn't anything like that because the MPEG4-ASP experience still had problems for the average user (it wasn't a big win on file size/quality, compatibility was not a given, people still had to pay for licensed players, etc.).

In contrast, I think H.264 hit the threshold where it's good enough for the average person and you basically never hit the case where a file doesn't work for the person you shared it with because even though it's license-restricted, most operating systems and browsers include support. Moving away from that is going to be hard because most people will not see much advantage — AV1 is clearly better on file-size but most people aren't hitting limits on a regular basis and the feedback loops are often missing (e.g. you hit play in Netflix on your phone — how many people would have any way to tell how much of their data plan that used?).