I can't say how the website I'm scraping would respond if I just went full throttle. But it's also just a matter of courtesy anyway not to make ten thousands requests per second.

Funny story - at work we once had a huge spike in requests from a single IP. We all crowded around, thinking it was some malicious hacker from France. How exciting - we're now interesting enough to warrant a DoS! Turns out another team in the company was just pulling all our data into Algolia to improve search. They were clearly not very courteous!

So on the other end (building APIs) I certainly do pay attention to traffic and have Grafana alerts set up around it.

I would block it, if I was the maintainer. As the linked post mentions, automated requests can "ramp up" at any moment, risking server stability. By preemptively blocking automated parsing (on a resource which primary usage is individual requests, not mass ones) I would avoid future problems for myself. Let them contact us via support if they really need an exception.

In general I would rate limit by IP anything connected to the internet.