Most engineers don't want to be co-founders, and this does not scale well in any case. That role comes with responsibilities that can't be executed by committee and drama/stress that many engineers would just as soon avoid. There is nothing stopping anyone from giving engineers a decent chunk of equity but it doesn't address the core issue of scaling reasonable comp.

A "founder" is not just another name for a very early employee. It is a wildly different experience. I've been both, multiple times.