With the right ARIA labels, accessibility shouldn't be too much of a problem.
I've found out that uBlock Origin has a setting that can block web fonts by default. This also allows me to unblock them on broken websites, so that's better than using the web font browser setting at least.
Yeah, I browse with a lot of NoScript and other blockers, and icon fonts often turn into little square boxes of "cant' display" or wierd characters. If the designers had actually put something on it that said what the icon meant, eg "share on twitter" or "about us" well, that would have been pretty useful.
It strongly implies a lack of testing, using semantic markup, and not complying with accessibility standards ... which makes for a poorer experience for many people, and a loss of machine-readability (isn't SEO important anymore?)