Guys, I'm on act 3 on rebel path. I went to the Lethian's Crossing, which is obrigatory in this playthrough, then i went to the stone sea and lastly to the burning library.
Everything ok until the beginning of Act 3 when the Seats of Power quest didn't update. I'm on my third playthrough in the game and I know that in this moment the quest is upgraded after talking to Fatebinder Calio so you can complete the 5 Spires.
BUT this didn't happen in this playthrough. WHY?? It`s because I didn`t choose to go to the Blade Grave? But if this is true, why can you go to the Stone Sea claim the other two Spires even if you didn`t chose to support the earthshakers or the stonestalker tribe? It`s not logical why the game would block me going to the Ocean Spire since I didn`t choose to go to Blade Grave this time.
I want access to the Oldwalls Breach so I can go to the Ocean Spire ande my 5th and last Spire!

I do not think what you are asking is possible. You need to make a choice regarding where to go and last time I checked it was not necessary to have all spires to finish the game either. They proably made the Stone Sea spires and the one at the Crossing available regardless of your choices so you would not have to miss out on too may spires (and there is barely anything worthwhile around them), but you hardly need all of them. This one is also not easily accessible without going through a major dungeon attached to it, since it is kind of bigger deal of the storyline in the blade grave to just find it.
Compare your situration to my recent alliance plythrough: I never went to the burning libary, even though there is quite an amount of artifacts there. I never went there because I made the choice to recruit others first instead of the sages, which had a lot of unknowns attached (and my char had no idea what else might have been there). So you want access to all spires plus all of the shiny loot you picked up at the libary as well? Guess you want a choice of locations in the Blade Sea to pick up the remaining artifacts there as well, because... your character had a hunch something was there?

The bizarre thing though, is the fact that on the Anarchist path, you can visit every area, claim every spire, and potentially end all edicts in the Tiers. Actually, I believe you MUST visit all areas on that path.

Yet, if you're on any of the other paths, you always miss out on one region's quests. Which doesn't make a hell of a lot of sense.

The devs should have used the time mechanic, that they used for the very first act, throughout the game. For example, there could be reports of something important occurring approximately N days from now, or on a particular date, and you need to finish stuff up before then - that way, the restriction on regions to visit would make more sense. Also, it would mean the time limit mechanic is actually used more than once.

It also doesn't make much sense that you're effectively being led by the nose by whoever you decide to "ally" with - you're supposed to be "independent" no matter which path you're on, yet you effectively become someone's bitch whomever you choose. But that's off topic...

Yes it's true that although the anarchist path feels more "freeform", there are definitely less quests per area - mainly because your only option is to kill everyone most of the time, since everyone considers you a traitor.

Still, this game had such potential that was ultimately unrealised. I was originally anticipating a tale of treachery, manipulation and backstabbing, but by the end of the first act we're choosing a side and then it becomes another bog-standard RPG for the most part.

Also, I really wish that the points where you could betray your current alliance made more sense. Generally these points were when you got to a new area (so it felt totally random), yet in other areas where it would be more logical (e.g. going against Ashe's plan to devastate the land) there is no option.

There also needed to be more places where you could provide judgements. Sure there were a fair few in there, but most of them seemed insignificant.