Replying to @null and @therevoltingx, @johnnyryan, @BrendanEich, @samtingleff, @acfou, @kickstand, @mrr619, @WolfieChristl, @johnwilander, @brave, @random_walker
That completely depends on what is done with the identifier, and under the GDPR it can never be in exchange for free content, otherwise it's not valid consent. This isn't "adtech bad", it's just the law.