Most subscriptions can be canceled with a few clicks, usually right after buying it without loosing the paid for time. If you cant manage your subscriptions, that sounds like a problem you should address yourself instead.
Your suggested solution of simply turning off the credit card the subscription is linked to doesn’t cancel said subscription, it just results in a breach of contract from your side. That only works cause most companies can’t be asked to deal with you, otherwise the subscriptions would continue and the incurring cost would sooner or later be sent to a collecting agency, with additional charges for late payments.