The main issue isn't the technology or the software or the CSS they use - but the fact that a majority of people don't know how to communicate. I say fix that first.
Also, the problem isn't being able to create groups or include or invite people as much as it is getting people to consistently use it to make it meaningful. My company has a wiki where we convey information, but guess how much information from the one-off conversations we have ends up there?
I think there is huge room for technology to solve these kinds of problems, and we've only scratched the surface.
However, in most small businesses (and lets face it, theres more SMB then there is large or enterprise customers hands down) the decisions aren't made on a wiki, or even e-mail for that matter. In a company size of 60-70 or less its still way easier just to walk over to their desk and talk it out. Who remembers hearing a conversation ending with "don't forget to put this on the wiki?" This sentiment being true in my own workplace, the wiki is still considered the de-facto documentation on a subject (guess how many pages are up-to-date).
I believe any successful business collaboration tool will fully grasp facilitating interaction in a way that meetings or quick one-on-one's can't. Having technology outpace human interaction when it is humans that ultimately have to fully articulate themselves I think is the largest obstacle.
TL;DR - I think I agree with you, but the real solution is still difficult to solve with technology alone.