Some student / beginner trying to learn and then getting smoked by a footgun is a weekly occurrence on the big cloud subreddits.
It's better business to have people beg for mercy and then magnanimously waive fee than to have any discussion about actual hard limits (which would be used by big corps too not just students).
Yes it can be done technically - Azure already has a not loudly advertised account type that is hardcapped. And no billing alerts aren't a solution. Hell you could even do opt-in "yes I understand my data will be deleted" hardcaps.
This is a fixable problem - they just don't want to because a fix would be bad for earnings.