Perhaps the fact that it's popular is exactly what those nay-sayers were worried about. They didn't want a more fragmented world of incompatible standards.
Some appealed to unrealistic things though, like “all decent text editors should help to make json typing/formatting bearable instead”. Yeah, that totally worked before and will work this time too. We’d all do much better if our standard formats weren’t such an annoyance to work with in the name of something that computers wouldn’t even notice eventually. If there is a void inside a busy place, it will be filled regardless. With that in mind, think what would happen if something much less adequate filled that void. They didn’t want world which couldn’t care less about how anyone wanted it to be. But that’s what we can only have.