> I feel like they could have a sustainable model if they had a more expensive one-time purchase and every few years released a new major version that required a one-time purchase again.
And people complain about this also. If everyone is going to complain anyway, they might as well go to subscription which is best for the business.
Do they? It's not super common, but I can think of the JetBrains IDEs that I believe let you continue to use the last version of the IDE before you stopped paying. Alfred, the Spotlight alternative for Mac does something like that, and you get a discount code if you own the last version.
And people complain about this also. If everyone is going to complain anyway, they might as well go to subscription which is best for the business.