'browser extension that "visits" random websites'
Dig deeper... Those kinds of plugins have existed for years, but with only marginal success. Privacy problems are so much bigger than that. There are so many firms involved in a chain, all betraying your trust... Aiding Big Tech and their vast spiderwebs...
Lookalike groups and custom audiences means Google / Facebook only need one low hanging fruit user in any circle to betray everyone and squeal up valuable personal info on a large swath of any circle of friends / family / colleagues etc.
So misinformation, won't cut it anymore. Most people I know never used real-names on Facebook / Gmail. Never used real address or phone number either. Yet we were all tagged together in friends lists & photos anyway. That's a warning sign.
How did this happen? Facebook / Google convinced corps to upload their CRM databases as part of the advertising process. ISP-Telcos / Banks did this routinely. Data brokers bought up peeps supermarket loyalty card shopping habits, along with address and phone number info. Experian slurped data from parenting websites... That's what we're up against here. So we all need to Box cleverer. As bad assumptions won't protect us!