They should turn fingerprinting to max and install uBlock origin by default.
It might mean millions of FF users would suddenly struggle with captchas, but it might also mean that site creators just stop using reCaptcha and similar.
Or, most 'regular' users will switch to Chrome because reCAPTCHAs work better in that browser. Firefox needs to make sure they're not going to ruin the user experience by breaking sites like this
It might mean millions of FF users would suddenly struggle with captchas, but it might also mean that site creators just stop using reCaptcha and similar.