When I mention the age of a performer in a review, I do it for a reason, a good reason.
When a former or current opera star, man or woman, is still singing when he or she is 68 or 73 or 90, it is worth noting and the reader should know. A critic’s remarks on that singer, positive or negative, should be taken in the light of that information.
When a conductor is 80 and leading a performance of “The Rite of Spring,” it would be wrong not to mention his age.
When a conductor is 22 and leading a performance of Mahler’s Ninth Symphony, ditto.
When audiences have known a performer as a child prodigy and that performer is now 44, you say so.
When a pianist is 85 and still playing Liszt or when a pianist is 26 and already has a huge international career, it would be unprofessional for a reviewer not to report their ages.
And so on. Get it? No insult is intended. Take it or leave it. Geesh.