I use Revolut with a disposable virtual card for sites I don't trust. So I can immediately delete the card.
Blocking the payments can still be a good idea—money you have in hand is worth far more than the dubious hope of a refund—but you should also keep clear documentation showing that you cancelled your subscription following the specific steps required by the contract before stopping payments.
A caveat is that one should be aware of how binding one's agreement with a business is, and whether a simple card cancellation will make the problem go away or become worse (collections).
I think major selling point was preventing fraud, and it was a hassle for a consumer. I.e. consumer have to proactively generate virtual CC every time they pay over the Internet. Which is a pain point especially on mobile. Zero liability solved the problem for the majority of users with less friction.
With regards to subscriptions virtual credit cards are not always a solution. If you have signed a contract and then your card "expired" it doesn't magically make your contract void. I know that gyms will keep billing you and eventually will sell you to collectors.