I haven't had Acrobat on any machine since I found something faster in the early '90s. I forget what, wasn't XChange that came later. Ah yes I can - Foxit. Not sure why I switched to XChange, might have been more features in its free version than Foxit Free.
Nor can I recall when FF got built-in PDF support, it must be at least five years ago. I've always been a minimalist, hence I always prefer bulltin to addin/plugin/bolton etc
BR