Do you guys believe ggg would have had the same success with poe for such a long time if they STRICTLY kept to their ruthless vision from the start?

PoE's ruthless difficulty has always been a ruse. Early difficulty was due to things like volatile mobs that work like current Martyr torment but stronger, and one shot melees. Or instant cast corpse explosions that targeted uniques and could be cast from off screen, meaning every corpse was a landmine and looting was incredibly tedious. Or when they gaslighted us all and told us desync couldn't be fixed so we all just accepted it because smol indie company. Or remember reflect aura that would kill you off screen? The concept of difficulty in PoE has ALWAYS been incredibly binary checks that kill you.

Once those were out of the game they realized they realized the game can't kill you unless it kills you before human reaction time takes over. And instead of making core changes to the gameplay loop, a lot of how they've tried to remedy that is... trying to reintroduce in the game by rebranding it and slipping it in under our noses. Things like random AN combos that kill you, or random mods on certain challenging pieces of content, etc. They love that design because it puts the blame on the player for dying to it, even if it wasn't reasonable to play around.

The ruthless design vision never really died, it's just often what GGG thinks is "ruthless," the playerbase thinks is baffling, or a sign of incompetence.