Because OpenAI built their entire business around shamelessly scraping anything that had bits on it.

Maybe. But scraping isn't abuse. Seems a bit different?

Quoting the OP

> These checks are part of how we protect our first-party products from abuse like bots, scraping, fraud, and other attempts to misuse the platform.

That implies that OpenAI (or at least this employee) considers scraping abuse.

Given that the scraping doesn't do any rate limiting and pisses on robots.txt, yes it is abuse

Is there any evidence OpenAI has been ignoring robots.txt for scraping purposes? AFAIK the main sources of that traffic are still unknown.

The top comment categorized scraping as abuse ("abuse such as [...] scraping") - that's precisely why some accuse its author of lack of self awareness.