I think there has to be a gradual on-ramp for things to pick up steam. You can't go over the "activation energy" required to set up the semantic markup etc. upfront that would have been needed for the Semantic Web back then (ontologies, RDF, APIs). Instead, AI agents can use all websites to some extent, even before you do any agent-accommodations. But now you can take small steps to make it slightly better, then see that users want it, or it drives your sales or whatever your site does, and so you can take another small step and by the end of it you have an API. Not to mention that AI agents can code up said API faster as well.