Back on topic: That the whole map is accessible at first and you must make decisions when you enter what area relative to your current powerlevel is part of the game. I think it adds to immersion when I see "I am not powerful enough for now", but have to learn and change, then I can come back (and beat that freaking Hilltroll that would have killed me before).
For me, that adds plausibility to the world the game is set it. Not everything is just "strong enough to pose a challenge". Some games do not need that to work (think Mass Effect, which has a different approach than Divinity, which is to "tell a smooth story", while Divinity tries to give you a world you can (relatively) freely roam and discover it (while it also tells a story).
The latter playstyle got a bit out of fashion in the last years as, from the late 90s onwards during the early 2000s, RPGs got mainstream. Divinity is a step back to that other playstyle (which at least Larian has never left, you could find areas that simply are too strong for you also in Divinity 2).
As this is a fairly known to most people playing this game, it is no surprise that a complaint about that openess creates "D'uh, what do you expect? That is what this game is about?" reactions, that sometimes are veiled, sometimes supressed, and sometimes stated very directly (which then comes off as rude).
