[diggan]

> If you start using Unity, you're not an independent developer any more

How so? The usual definition is that if you're self-publishing, you're independent, but you seem to go by some other heuristic.

> has there been a point where Unity did not require a subscription yet ?

Yes, up until 2016 Unity sold "normal" paid licenses (as well as offering a free version), meaning pay once and keep using, rather than subscription-based like it is now.