I suspect that has a lot to do with billing monthly for an annual plan. That leaves people deciding whether to continue paying for a service that they are not using or paying out a penalty in excess of the monthly rate to terminate the service. Both options leave the impression that the company is trying to punish the customer. Contrast that to paying for a year upfront, where the customer is more likely feel foolish for paying for something they did not need.

I think the angriness was from Adobe refusing to cancel now effective at the end of the contracted year - i.e. making a simple "does not renew" note - more than 30 days before end of contract, or somesuch. Therefore catching forgetful customers paying for a second unwanted year. "Understandable", as they say.

I think GP means "cancelling doesn't get you a pro rata refund" (which you wouldn't expect if billed annually) rather than you literally can't cancel :)