why would you compare the two? seinfeld is actually funny because it's universal social observation. it's a streetwise comedy of manners like curb your enthusiasm.
we've all been george when he leaves a dumb message on an answering machine and then stresses over it; we've all had touchy friends or acquaintances who cut ties for some petty reason. it's often exaggerated, but it's human and relatable.
i wouldn't just question the taste of someone who doesn't like seinfeld but i'd question how much awareness they have about everything going on around them.
some jokey sitcoms still hit--frasier and golden girls are witty. but most aren't funny anymore and they weren't all that funny in their day.