You don't think the lessons learned by those developers' experimentation weren't shared and applied in the decision-making process for more prominent distros?

You don't think the lessons learned by those developers' experimentation weren't shared and applied in the decision-making process for more prominent distros? Sometimes. But there is also a lot of 'let's take Ubuntu and change the default desktop/wallpaper/DVD package set/...'. Also, it's not as if developers in major distributions such as Debian don't have room to experiment with different approaches. For instance, in Debian, the default init system discussion rages. The most promising candidates are already available in Debian itself.