What you're referring to are LLMs visiting your page via tool use. That's a drop in the ocean of crawlers that are racing to slurp as much of the internet as possible before it dries.
Not to me, but I've known people who have had their sites DDoSed out of existence by the scrapers. On the internet, it's often the smallest sites with the smallest budgets that have the best content, and those are hit the worst.
> They do provide source for material if users asks for it
Not for material they trained on. Those sources are just google results for the question you asked. By nature, they cannot cite the information gathered by their crawlers.
> You still need to pay for the traffic
It's so little traffic my hosting provider doesn't bother billing me for it.
> and serving static content (like text on that website) is way less CPU/disk expensive than generating anything.
Sure, but it's the principle of the thing: I don't like when billion dollar companies steal my work, and then use it to make the internet a worse place by filling it with AI slop/spam. If I can make their lives harder and their product worse for virtually no cost, I will.
Do they do any harm? They do provide source for material if users asks for it. (I frequently do because I don't trust them, so I check sources).
You still need to pay for the traffic, and serving static content (like text on that website) is way less CPU/disk expensive than generating anything.