I think this is an argument in favor of doing automatic PDF -> HTML conversion for the authors that don't want to touch it, but I don't think it's an argument against letting those who are fine with HTML provide their own.
HTML is not generated from PDF. Both PDF and HTML are generated from LaTeX.
Probably only a small percentage of people are using latex today. I’ve never personally seen it used. Just MS word docs sent to coauthors then to the paper editor.