It might be better framed as "half the Internet's traffic comes from a subset of power users who automated their interactions with the web." Maybe we need less "agentic design" and more APIs.
There's a unique social stigma around "bots" that isn't applied the same way to power users of any other system (understandably so, given some are nefarious). I believe this largely gave way to AI-powered bots, as there's a demand for bots to behave as humanly as possible to 1) minimize obstructions like 403s and 2) maximize the extraction of information.
Maybe if web servers were broadly designed thinking of bots as power users, the web would bifurcate into a "optimized web" for bots (APIs), and a "traditional web" for humans (HTML). Instead, we're getting this mess of bots and humans all trying to squeeze through the same doorway.