I think you miss the point of people saying this because it is entirely based on circumstance. There is no diminishment of Ukraine going on here. This would be said about any country that was being invaded by its neighbor where that neighbor asserts that the country shouldn’t exist. Particularly when those countries used to be joined together. It is exactly like saying the UK has the right to self determination by leaving the EU. It is simply reaffirming and stating a fact. And in fact people do say this about other countries. Particularly right now about Finland and Sweden joining NATO and also about Taiwan.