Similarly confused, I use profiles heavily every day

It may be due to my workflow; I simply hit a key combination to either open my personal profile or the one for work, for example.

Nothing fancy... The -P option for Firefox along with the usual key bindings for my window manager

Personally it's the integrations. I have a Chromebook, which integrates with GSuite, and integrates with Android. I can manage extensions, permissions, etc, all from there. This is important since I use this Chromebook for work, but it would be cumbersome to run Firefox and Chrome simultaneously.

With Firefox I get just-a-browser, and I need more than that. If Firefox had a way for me to manage the browser across devices it would be more viable for me.

First, you can sync your browser with your Firefox account, so this is I guess what you want?

Second, for the Google (Gsuite, Android) integration, you could just use a work browser (aka Chrome).

Third, if you use all that Google stuff in your private life, I don't really see why you would be worried about Manifest 3-related privacy and ads/tracking matters anyway. I mean, Google already has your data.

> First, you can sync your browser with your Firefox account, so this is I guess what you want?

Maybe? Probably not though. For example, with GSuite I can manage the settings via the web UI and then have policies that enforce that those settings are verified correct.

> Third, if you use all that Google stuff in your private life, I don't really see why you would be worried about Manifest 3-related privacy and ads/tracking matters anyway. I mean, Google already has your data.

I opt into Google having my data, but I want to be able to opt out of running arbitrary content in my browser. uBlock and uMatrix give me that, Manifest v3 takes that away.