Not dumb... Looked at this a few years ago.

My theory... the classes that race three or more on the team are far more popular... the social dynamics seem easier to manage then two man teams. You can be succesful with a range of skills on the boat... you don't absolutely need two strong sailors... You can still compete with a newbie on the boat as one of 4. ... try that with a spin cat... A newbie = No fun in a competitive race..

The Lightning Class has been strong forever... always leads the OD rankings.

The Melges classes all have great factory promotion behind them.... High profile events that attracted a wide range of sailors at their kick off. The M24 took off with lots of rank and file support... then it elevated to a gran prix level... which saw rank and file support fall off as the pro's took over and the M24 still remains strong at the semi pro level..

the new Melges 20 has a gran prix circuit that already trumps any catamran circuit... but it's not close to the M24 tragectory.

Now look at the J80 class... It is really taking off like wildfire! again... race with 3 or 4 on the team...

My take... these boat fit the market niche...social and competitive.
(They also don't capsize.... people have big issues with capsizes and swiming as part of sailing)

Cats have tried the more then two crew...
The swiss lakes have these corporate sponsored Decions 35s... the class has no rank and file appeal... Why? It's a lot of boat to handle... You don't put a newbie on that boat and survive a breeze.

YMMV