So it must be "Rent" now? Logically you still purchase a subscription. So this is a very weird solution.
A better solution would be that it has information on what you're buying. "You can use this even if the game is removed", "You can play this online and even without starting up Steam", "Dedicated servers will be released when the game is stopped", etc etc
I think (see: hope) this is a stop-gap solution. It's at least better than the current implication of buying something and being able to keep it despite these companies knowing full well that the game will be gone in a much more permanent way the moment they flick the switch on the servers.
To paraphrase Ross Scott, it may be a bare minimum but it's at least nice to have it in writing just how fucked we consumers are.
Your counterexample, "purchase a subscription", actually undercuts the point you're trying to make. The goal is honesty here. If you are renting or subscribing, you want to know that up front, in big text, using the simplest possible word. That word is "RENT".
The issue about the lease business model being bad for society and consumers is also important, but it's complicated and different from basic truth in advertising.
rent implies a continued fee though - i’m not sure a once off fee to play a game that can be rendered useless at any time covers that? rent would be more like $10/mo rather than $100 for as long as the game is available
Except you can't make Steam offer their content offline like that. By altering the language they use it effectively makes them more transparent about what you are really paying for. So, in order to use the word "buy" or "purchase" they would have to make the content available offline, or they have to use a different word that essentially means "rent" or "subscribe" cause that is what is actually happening.