> They never attempted that
Oh, but they did[1]. You might have missed the initial drama as it transpired because of their quick U-turn (to their credit). I have reason to doubt the subscription plans they published which clearly stated that failure to keep up with the subscription would lead to bricked IDEs. JetBrains only backtracked[2] after receiving sustained pushback. There were HN posts for the initial bricking plan[3] and the backtrack[4].
1. http://bytecrafter.blogspot.com/2015/09/how-jetbrains-lost-y...
2. https://blog.jetbrains.com/blog/2015/09/18/final-update-on-t...
They never attempted that. You were always able to use the version you paid for, even if you stopped your subscription.