Short answer is "no".
Long answer require some technical knowledge that you clearly don't possess and would just give you an headache.
To put it simply, if your app get successful and lots of users adopt it, you are bound to exceed those arbitrary limits.
Thing is, offering free api is not sustainable but you could offer some half way option, like including some ads in the apis responses as well and have the devs agree in showing those ads (I'm talking banners and the like) so that you can assure your ads clients that they are going to be shown anyway even by third party apps.
If course you can then go nuts on the penalties for infringing that agreement.
What is Reddit doing is basically saying, you can use our APIs if you are doing a school project.
I mean, the only "rude" part might have been telling OP that things would be too technical to explain but if you read the OP message he's saying that himself, I just justified why I'm not going much into details.
In fact, OP didn't feel the need to respond that he was offended, you simply felt the need to project into him.
You don't need to reply, you know?