Because the point was never to monetize the APIs. The point was to get rid of the third party apps. A minority of users are still using the not monetized versions of reddit. old.reddit.com, and the third party apps. The people using new reddit, and the reddit app, have a totally different, heavily monetized, modern social media experience full of ads and suggested posts. They want everyone to either have that experience, or leave.

But they can't come out and say that, because it's a huge fuck you. A fuck you to their original members, a fuck you to the apps they used to fuel their growth for a decade. Now they want a controlled ecosystem like Facebook, but they can't say it directly. So instead it's surprise API costs, refusing to talk to app developers, lying about conversations with Apollo devs.

But just like everything else they do, reddit can't plan for shit. So they didn't at all consider the fallout for accessibility tools, mod tools, etc. Which is why all their messaging since then has essentially been "No, we weren't trying to kill accessibility and mod tools, just the third party apps for normal users!" But they can't say the second part directly.