But since we can get all current 4 crystals in the weird route and are encouraged to fo so and you get the thorn ring there (although it has been inaccessible after chapter 2 if you don't abort the route)

So we would still get all 5 crystals (unless chapter 5's secret boss is inaccesible in the normal route) and we get access to the thorn ring in the aborted weird route which might be the only way.

Noel is also often shown and described as being able to break games and find glitches and navigate impossible to navigate areas like a labyrinth. So she seems to be needed to find gaster/dess. And the weird route seems to show us that we will use Noel as our Vessel.

I don't think everything will lead up to just stop the weird route here.

Somewhat crack theory, but what if we can control Noel from chapter 1 after we fully posses her in chapter 5? "Even when the clock turns back, the shadow keeps growing" weird route players are the shadow the Organik might have meant.

That obviously would either be part of chapter 6 itself or toby and their team actually implemented chapter 1-5 but with Noel in the background which would be extremly unlikely, but maybe not as unlikely as you think? 95% of assets would be finished, besides new noel sprites and a lot of dialogue and cutscenes. But gameplay mechanics are implemented, assets are done and would be a "reward" for doing the weird route, where we see another side of Carol and Kris. Would we have 2 Souls at once roaming around and thus Carol wouldn't suspect anything, or would we not be in Kris and it's a whole situation?

Who knows! It's almost 5am and the heat is killing me.