I think the simplest explanation is that developers used it and did not like it.
The pro-XML narrative always sounded like what you wrote, as far back as I can remember: The XML people would tell you it was beautiful and perfect and better than everything as long as everyone would just do everything perfectly right at every step. Then you got into the real world and it was frustrating to deal with on every level. The realities of real-world development meant that the picture-perfect XML universe we were promised wasn't practical.
I don't understand your comparison to containerization. That feels like apples and oragnes.
The pro-XML narrative always sounded like what you wrote, as far back as I can remember: The XML people would tell you it was beautiful and perfect and better than everything as long as everyone would just do everything perfectly right at every step. Then you got into the real world and it was frustrating to deal with on every level. The realities of real-world development meant that the picture-perfect XML universe we were promised wasn't practical.
I don't understand your comparison to containerization. That feels like apples and oragnes.