It is obvious why people climb Half Dome, it is breathtakingly spectacular, beautiful beyond compare. The rookies climb it for this reason and because it is well known and accessible. If they were knowledgeable about other options in climbing, they would not be rookies.
I don't think many people climb it because they want to be immersed in a crowd of people. I've never heard this as a motivation for anyone to climb a mountain. Where is the proof that that is their motivation? Inexperienced or experienced people go up there because it is beautiful, and they want to experience the beauty. Sure, there are some bragging rights involved, but I'm sure the boast factor is not part of anyone's agenda on SP.
I climbed Half Dome in 1972 when I was 12 years old with my father and two brothers. We saw maybe about 15-20 people on the entire trip, with a half a dozen or so on the summit. Nobody was on the cables but us. (Some hippie stole our food bag at the base, which pissed off my father.) We did it for the reasons mentioned above.
Nobody is born with crampons on their feet or a "rack" around their waste. You have to start somewhere. I don't like crowds of people when I'm hiking/climbing, but to other people I am part of the crowd.