I really really dislike this. Why does google get to decide which websites are good and which are not. Unless someone subscribes to this service google should do what it does best, search. One day they decide everyone should be mobile friendly, the next day they decide which sites are bad and which are not, what more? Every single day, google is giving me more reason to use alternative search engines.
Nobody is being forced to any attention to their pronouncements. The only reason they are of any relevance is that a lot of people freely choose to use services and software that incorporate them.
Not necessarily true, your website being flagged by Google can get you blocked on multiple browsers. That's enough to destroy your traffic. Granted, I'd say 99% of these are legit flags from JS injections, etc.
Sure, you could use a browser that doesn't do this...but, you won't.