Problem is Adobe's minimum contract length is a year. The monthly price quote is that price divided into months. After a year or two you could have afforded to outright buy it under the old regime.
They do have a monthly version which is a bit more expensive than the yearly-pay-monthly one they show. It’s hidden behind a click or two, but it’s there on the plan page. I know, because I considered it before choosing the yearly contract.
But yes, with subscriptions, it would be cheaper to buy it outright, but not everyone has that luxury. We can argue all day about whether people need Photoshop or whatever, but the best option (IMO) is to allow subscription and purchasing and let the user choose. Then those who can afford the $300+ up front can spend that while those with little disposable income can spend $10/month.