What you're talking about, where you simply generate a set of random splits across features, is Extremely Randomized Trees (https://link.springer.com/article/10.1007%2Fs10994-006-6226-...).
Another difference is that RFs use a bootstrapped dataset and ERTs use the full dataset.
In any case, I agree with the thrust of your original comment that the specifications of the RF algorithm can be relaxed, usually for performance reasons, and still retain strong performance. But this goes back to my original comment that the performance considerations of random forests often aren't highlighted to new learners (whereas introducing ERTs to a beginner would probably shock them - how could you take totally random splits and still get any reasonable performance!)
You are correct. For classification the usual rule of thumb is to select square root of the number of features.