Been useful at communicating that they feel someone is confusing expectations with rights? Yes, that's why there is a word for it.
Also, I get it's annoying to hear entitled, ad hominem, logical fallacy, privilege, and other currently trendy words being over used and often misused. But I'll take it over what there was before that, which was no discussion at all at that level of abstraction most of the time. The places where these words are overused are places where the community is learning these concepts.
In this case, calling someone entitled is actually a compliment, not an ad hominem insult or put-down, because it acknowledges the poster's humanity.
The proper response in this case would be, "Why, yes, I probably am a bit entitled, like most people. Thank you for recognizing that I am human."
Not useful, and more over, it's ad hominem.
Claim: Turing was wrong about the Church-Turing Thesis because he was a homosexual -> ad hominem
Claim: Turing was immoral because he was a homosexual -> not ad hominem (although still not a good argument)
Has calling someone entitled ever been useful? For the last few years it's felt like nothing more than a petty "you're wrong" remark with bonus condensation built right in.