You can oversell capacity in two ways: 1) You have enough slack that your edge case top-end users can utilize what you advertise, and there are enough people n

You can oversell capacity in two ways: 1) You have enough slack that your edge case top-end users can utilize what you advertise, and there are enough people not needing it that this is all fine 2) You do not have enough slack that your edge case top-end users can't utilize what you advertise, in which case you are, at best, being deceptive in your advertising practices. No one cares about the former, and even though the latter is common place, that doesn't mean that it isn't a shitty advertising practice nor should someone making use of a provider have to know that this is common place. You should be able to reasonably expect to get what a commercial entity is advertising itself as giving as part of your payment to them. Just because this industry has been garbage about it doesn't mean that it should always be garbage about it.