Some products or services, every customer needs about the same amount, or the same minimum amount. It seems reasonable to have a maximum allocation in a crisis for those.

If different people need vastly different amounts of something, either they are able to judge, in which case prices work, or they are not, in which case some independent means of allocation has to be used.

I don't think waiting in line is a good method, but that doesn't mean unregulated prices always are either.