If the West keeps escalating, at some point Russia has to respond to not loose credibility.
Russia already lost all its credibility, after they sign the Bubapest memorandum, they breach it and annexed Crimea. Then tried to annex the rest of Ukraine (or to put one of its puppet) some years later. At this point everything Russia sign has less value than the paper used to write it.
You are right, nobody want WW3 but it is not that because of this then Putin (or everyone else for that matter) could do whatever he want.