Why not? The web of late '90s (as I remember it) worked just fine without those. Ability to serve only documents but not programs, and inability to persist any

Why not? The web of late '90s (as I remember it) worked just fine without those. Ability to serve only documents but not programs, and inability to persist any identifiers would mean that both website developers and visitors would know that website cannot be disruptive, and would serve content (or nothing of substance at all). I expect that advertisers won't go there because it contradicts modern beliefs in targeted advertising and how behavioral data obtained by tracking is worth everything. And it's virtually impossible to distinguish between paid-for "native" advertising and honest product recommendation.