From turbo capitalist perspective, your work is uncaptured value. A version of photoshop you buy for 300 and don't buy again denies Adobe access to revenue you would be making over time. That purchase gets "cheaper" as you divide it over the life over jobs you do. With subscription, there's a limit to how much upside you get / month before paying again, and allows them to change the terms of the deal as time goes on to suit them.