Regardless of the regulation. What is the difference of being in the US or anywhere else if you can't go on campus and only work /study from home. The quality of learning is low in both cases.
I know locally that has been one of the biggest stumbling blocks for the local schools, dealing with students that did not have good internet.
Another I can think of is possibility of re-entry. Last time I heard the USCIS was virtually frozen for visas and all. If these students leave for this year we don't know if they'll be able to come back once the pandemic is over.
For merit students with scholarships it is almost impossible to finance a both-way trip on such a short notice.