It's not that deep. "Twitter" just has more cultural mass than "X".

This is like correcting someone who says "legos" instead of "Lego": who cares what a corporation wants you to call it?

My point is that once a word get's adopted in the global lexicon, it's not easy to unseat it. Doesn't matter if that word is a brand, a misnomer, slang, or even derogatory to someone, it will stick for quite some time. Companies and websites get rebranded all the time and can be done so overnight. Language doesn't move at that speed.

I'd argue that it doesn't help that X is such a stupid name that many people actively oppose calling it that. Twitter (noun) and tweet (verb) were hardwired into language, my guess is you'll still be hearing them in decades to come.