Why exactly are you hung up on the "voluntary" aspect when it comes to the UK yet say diddly squat when it's demonstrated this is exactly the same as in every country in Europe?
If you have a problem with one and not the other, that's called hypocrisy.
Captive?! Give your head a wobble! Westminster is the sovereign power and CAN say no forever if it wants to in the same way the USA, Germany, Spain and France have.
Yet the UK hasn't said that! It's merely said "now is not the time" which us highey reasonable!
USA, Germany, Spain and France do NOT go to that extent.
Given this and the fact there IS a mechanism, Scotland is so far from "captive" its not funny. Do you have a problem with the UK Government having total control over any border poll in Northern Ireland?!
You'd be wrong if you did.
Under international law, the UK and other sovereign states are entitled to full protection in law of territorial integrity. So, no, devolution is not pointless. It's the limit of self-determination Scotland et al is entitled to. The SNP should concentrate on running devolved affairs and not independence. Not pointless.
"A vote for the SNP is not a vote for another independence referendum." - Nicola Sturgeon
For someone who isn't bothered, you sure do post quite a bit on the issue!