Gate Progression

I've heard GGG wanted people to earn progression in the endgame.

then why dont they gate map progression behind an actual hard boss or map?

because from what im experiencing right now, with my own ethical, custom, non pob, ssf build after having played the game only for 900 hours.

I'm wondering why I am allowed to do tier 11 (red) maps when my not-dying-tier is maybe around 7-8?

nobody likes random one shots and I just ragequit because of that BS. (i only play a 1-2 hours anyways, because i cant progress fast enough anymore and im no grinder...)

so if they want players to earn their progression, why are they ignoring that fact?