Well, first of all, it's not "prohibited", it's "prohibited without a consent". Second, less personal data - less useful (relevant) ads, less revenue for Meta - less investment in R&D, less open source/research, more focus on "gathering contextual portrait". Which... won't end monopoly if that's what the general public on HN wants (hard to say what this whining is all about). Maybe more advertisers will go to Google instead (if the ruling is only about Meta).