As someone who is hosting a Quilt Along right now, I'll put in my $0.02 about why faster methods are not used.
I'm embarking on two Quilt Alongs simultaneously - one for the AccuQuilt GO! and the other for the AccuQuilt Studio. Both projects could also be rotary cut.
Because it's also a Mystery Quilt (blocks are posted one at a time), the cutting methods are not necessarily as efficient as they could be. Also, the quilts are about USING the dies, so I'll have people use their die to cut something even if the rotary cutter would be much faster for that block.
I would suspect that someone coming in to the middle of the Quilt Along, without knowing the background, and at first glance, would think it terribly inefficient. But for the people doing the Quilt Along, they are quite happy to learn something new, and for them it's more about the journey than the destination.
So, I guess different Quilt Alongs have different purposes, and there's something out there for everyone. Some people chose not to participate in this quilt along because some of the blocks require curved piecing. Well, maybe they will find another quilt along that is more their style, or the next one I do might enable them to participate.
Also... there are many different ways to eat an elephant. I would consider "Thangles" to be a newer way of piecing triangles, but I wouldn't question someone for not using them or preferring to do triangles the "old" way.