Moral high grounds don't mean much these days. They are weaponized as a way to get an advantage in an argument.
If the purpose of every argument is to prevail, then sure, invoking morals in any discussion can seem like a tactic. Moral hypocrisy can be particularly exhausting.
If the invocation of morals is always evidence of manipulation, though, then any ethical position can be easily dismissed.
Moral hypocrisy is cynical. But that doesn’t erase the value of morals and ethics. Morality, sincerity, and rhetorical effectiveness are still very different things
You cannot use a moral high ground unless you’ve earned that high ground through your past behavior.