Most websites are exist to make money from specific audiences in specific ways, often defined in contracts between hundreds of business entities, and none of them want you to be able to automate access, or interact with the website in any way other than the one that spins the money-making machine. Consider that the flip side of "basic tabular interface" is "skip website entirely, access underlying database"; the flip side of "screen readers" is "ad blockers"; the flip side of APIs is "competitors can scrape my listings and use them against me", etc.
Agents are hot right now, the whole business side is still blinded by hype, so things like MCP and .md endpoints are not just getting a pass, but are even pursued by the business people ("we have to do something with AI!"). This won't last long, though - they'll soon realize their mistake, close off access, and enshittify the web some more.
Just like they did in the past - e.g. when APIs and mashups briefly became a hot thing, then went away as businesses realized this defeats the very thing that makes them money: total control over platform/user channel.
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[0] - Even your most basic blog showing some ads creates a money-making chain, made up of dozens or hundreds of business entities, bound by actual contracts, and the "blog author that just wants to show some ads" is merely one party at the end of that chain.