Except that the NATO treaty is quite explicit: it exists to defend a certain geographical area. What you are arguing for is either that NATO members act in ways not mandated by the NATO treaty as if they were committed to do so under the treaty (a very bad idea, IMO), or a change in the NATO treaty.... If NATO agrees, as a unified organisation to deploy and act in a war zone then individual countries should not then be allowed to unilaterally introduce restrictive caveats removing their forces from harms-way leaving other countries to do the hard yards. Would Germany for instance have accepted a situation whereby NATO members - America, Canada and the UK, having deployed to Europe then suddenly and unilaterally decided to introduce restrictive caveats stating that they will neither fight at night or get involved in direct combat with 5th Guards Army - I seriously doubt it?
Also the common excuse that NATO is there to defend Europe, so we shouldn't be in A-Stan is no longer valid. Unless NATO changes to address a new array of global threats (failed states, assymetrical warfare, terrorism, climate change impact etc.) and accept that it will have to get its hands dirty outside mainland Europe and operate under unified ROA's then it's doomed to history.
That's the crux of the argument about NATO being "there to defend Europe". That's what the treaty says it's for. And North America, of course. If you want to change that, you should change the treaty. If we ignore one provision because we don't like it, we're saying it's OK to ignore other provisions, & bang goes the whole point of having a formal treaty. How can we rely on the commitment to mutual defence, if we've agreed that the treaty is no longer relevant?
BTW, IIRC the NATO operation is voluntary for members, precisely because it's outside the scope of the treaty. Defending Germany from the Red Army was entirely within the scope of the treaty: it's what it was written for. There was no possibility of partial opt-outs without breaking the treaty. The two situations are completely different.