That was the case a few years back, but look at how much they're putting in APS-C cameras today. Anything above 15 is pushing it really. Yep, moire rarely happens and when it does it's easily fixable. I've only had it happen twice with my M8 in the past 2 years I've used it.
Yeah but this is the dslr thread (and we sometimes mention mirrorless cameras) all of which have large enough sensors to mostly avoid the "too much pixels crammed in" syndrome. The key is to go for "good" pixels. A 12mp 5D original trumps practically every camera out there if your goal is image quality and a used one can…