That could consume as much, if not more, resources as returning real data

Returning some text files from the server fs is _wayyy_ lighter than letting the bot go through the search, middleware, and db while crawling your stuff.

Or just sending it a tiny zip bomb, or even just some sh*t right out of /dev/random

Bots are pretty good at detecting and preventing this kind of issue. Dumb clients would still be affected.