The main issue is that the attention economy and social pressure are so hard to break. People keep using WhatsApp because it is convenient and everyone is there. There are no other reasons.
The major other reason is that it is free, and most people are money-constrained.
Personalized advertising is a progressive tax. Because the rich spend more and the poor spend less, Meta et al makes more money from the rich than it makes from the poor, while offering the same service to everybody else. As a result, we get the educated rich upper-middle class complaining about advertising, while everybody else is happy about not having to pay their long-distance charges any more.