Also, there's an increasing push in internet marketing circles to get people to sign up for things, even free things. The reason is that it bypasses a lot of antispying tech and law.
At the same time, not having a mailing list is suicidal when big tech is ramping up erroneous removal of accounts, pushing users elsewhere (Twitter potentially. And Facebook has reputation of being for old people now), or killing organic reach (Facebook since a few years back: pay up).