Mozilla good, Apple bad
Mozilla are doing this for noble reasons, Apple less so. Mozilla is positioning itself as the browser which actually protects user privacy, rather than just blocking a few cookies and adding a few tracking blocklists. With Firefox, you can isolate every site from one another with namespace-based isolation and enable proper fingerprinting resistance with a couple of simple about:config tweaks. Safari doesn’t do isolation unless you explicitly PWA things, which sucks by comparison but I guess is still better than nothing.
The truth on the Cupertino end is that Apple doesn’t want to allow hardware interaction because it makes PWAs useful enough to act as a viable alternative to native apps from their App Store. Anyone who grew up with addictinggames and newgrounds knows what WASM+WebGL+WebUSB can do for those who want to build 2021’s equivalent of “free flash games” without the walled garden getting in the way.