Yes.
Yes.
The two statements are not to be combined to say that one should never have access to a\clearpage command, just that one should know how to use it properly.
We might agree that LaTeX insists that its final output always goes to a finitely sized “page” object while markdown insists that its final output must never be forced to finite dimensions. The detriments in LaTeX appear when you try to write a Web-page with it. The detriments of markdown appear when you try to write a structured document with it.
In summary, I spend too much agonizing time trying to use ePub formatted textbooks effectively, hence my strong dislike to join the “markdown (and equivalent) is the next best thing in document editing” band wagons.
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JJW