Loudspeaker crossovers from better manufacturers of speakers are normally very, very durable. They use good quality capacitors (the inductors are truly very passive components and do not age) which are not subject to any great stress and although dielectrics can age you would be unlucky to have that problem. Incidentally, I have some 65 year old audio equipment that is on its original electrolytics even though they were designed to last only 10 years!
Why does your friend think the crossovers need attention?
Cinema: 861v8, ID40, HD621, 800v4, DSP5200SE(2+C), DSP3300(4), DSW, + various recorders and streamers.
TV+Music: AC200, MS200(x2), Explorer2, QNAP, DSP33(2), 104 Tuner
Music: All Quad incl ESL63 + Gradient Subs(2).
Spare: 101, M2(2), 207