Now QML has its warts for sure, but it benefits from being designed with well-known use cases in mind, so it has lots of features suitable to them.
HTML was designed for structured, flowing text documents and everything else got bolted on top with only partial awareness of where the journey was headed (reading up on the origins of stylesheets and the relevant discussions is interesting in this respect). As a result it's just a mess for what it's used for now, pain-alleviating salves like flexbox notwithstanding.
When I do any non-trivial UI in the web stack, I can feel I am in continuous workaround territory. I'm trying to bend something ill-suited to my will. I don't get that feeling with QML.