This is bad why exactly?

and hamstrung browsers that are all basically Safari

Content blockers work in original Safari. Which part don’t you like? Content blockers as an app, safari itself, or inability to load third party js into every page you visit?

I wish PC browsers had something like that, because while I trust uBlock Origin (and others, e.g. Bitwarden), there’s always a chance someone hacks into their repo. Modular integration - separate Bitwarden and Adguard apps - is objectively better for these use cases than just pouring some javascripts into every website.