"Perform the Marxist reality check you are so proud of being able to do." Easy: The entire thread about Ukraine, plus link with aircraft carrier smoking and planes crushing. Pick your choice.
End of my answers to you until you accept civilised debates and stop practicing personal attacks.

"Yet, while it began as a defensive alliance to prevent/respond to Soviet aggression" I like this answer. NATO was created before the Communist equivalent. But yes, it was preventive.

"In that larger spirit, is not a somewhat more "forward" stance by NATO likely to be the best route to curtail Russian expansionism in the Baltic and towards the Middle East? After all, Putin has already demonstrated a willingness to "cherry pick" portions of the old Tsarist/Soviet sphere of influence and bring them under the Russian umbrella where he feels he can get away with it": Agree, but you cannot hope the one you are targeting will not see it and react. And it is kind of asymmetric warfare, except Russia can still obliterate Earth several times but can't invade for real a small country without extreme difficulty. And again, NATO is doing exactly the same, following the pattern developed by the USA, especially in Central and South America (but not only). I know it is a bit in the past, but USA got involved in Vietnam in organising a Coup against a Vietnamese Nationalist and installed their puppet.
And NATO/US get away first with Yugoslavia then with Kosovo, so spread the model until Ukraine where it failed. Putin's operation on Ukraine is a copycat of Kosovo. Same pretext, same modus operandi, and almost same results. Anexion of internationally recognised part of a sovereign Country, with the same disdain for international law and treaties.
If US/NATO can curtail russian expansionism (Reminder: Kosovo was invaded and carved from Serbia before Putin), so Russia can curtail NATO expansion...

"It has always been a pressure group [we are all saying the same thing, so you better listen] to promote the defense of Western interests" This I will disagree. It was used to promote US interests. If one western power was doing something US didn't like, NATO support vanished as in the Suez operation. I don't blame US for this, I blame others to ignore this reality.
Perhaps Iraq is the ultimate example of this.