I'm confused by anyone who demands Ukraine should cede territory and denies they can ever join NATO. Have fun seeing Crimean/Ukrainian/etc. conflicts repeat every few years while Russia keeps learning the lesson that imperialism is back in style. Are these people literal children, or Russian bots?
Ukraine agreed to give up their nukes as part of the Budapest Memorandum which Russia shat on, and the United States showed how little their security assurances were worth. The sad reality now is Ukraine could be admitted to NATO tomorrow and it would not matter one bit, because our current president believes himself a king who cannot be forced to abide any previous treaty, law, or norm of human decency.
"Valid" as in feasible? No. The war was started to keep Ukraine out of NATO, and Ukraine wasn't fully backed by NATO in the war because it isn't willing to go to war with Russia just for Ukraine.
I'm not an expert, but have read a decent amount on this. Others may have more and better info.
With that said, even if an Article 5 invocation won't bring the US into your fight, it provides a hefty infrastructure of value to countries in it. From basing, to logistics, to intelligence, to aid, it is valuable. Now the politics of it are complicated and the US can hinder some of that value, but it still means that in Europe if Russia provides an Article 5 reason, other countries in NATO can choose to help in various forms. That's not nothing. It's also faster and less arduous then negotiating individual defense treaties with neighbors and others.
So yes, overall probably still worth it. Even if just as an entree into other alliances.