I think you're mostly right - I'd just add that perhaps the lack of (real estate) space on most mobile devices discourages wasteful and hard-to-henpeck toolbars

I think you're mostly right - I'd just add that perhaps the lack of (real estate) space on most mobile devices discourages wasteful and hard-to-henpeck toolbars. Plus, as others have pointed out, there's that 1/2 MB entry fee. Expensive on transit and on local resources. Maybe also a correlation with the kinds of people who write nontrivial text on their mobile devices, and are comfortable with in-line markup?