It's hard to disagree with you, never-the-less it's also hard to hear Tiki take a bashing (although justifiably so). I think we can say that it's a great piece of open source software with the right ideas and intentions but perhaps not always executed well.
Unfortunately the way the community works here at the moment is that the majority of support falls on a handful of longstanding contributors (not developers per se) like Xavi. It's the same old problem, many users only a handful actually active. Of course this problem is mitigated when you talk about sites like Joomla who's user base is probably significantly bigger than Tiki's. So it becomes a numbers game, if you have a million users and only 1% of them are active, that's still a big number. Tiki probably doesn't have a million users.
One of Tiki's strengths is in it's adaptability and customizability. Unfortunately this also leads to its weaknesses; it's incredibly complex. Documenting Tiki, all of it's features and nuances is no easy task, programmer or not. Where something like Joomla can somewhat skirt around this issue is that it offers lots of 3rd party plugins, which means that the burden of documenting falls on the 3rd party, not the developers of Joomla. Tiki takes a different approach.
I'm not making excuses for Tiki, I'm well aware of it's short-comings. However, it makes me sad because I honestly think it's actually a great application, and there is a great community spirit, albeit partially obscured to the casual observer. However, somehow Tiki rolls on. Perhaps Tiki will one day gain the popularity of the likes of Drupal and Joomla, and thus gain a small army of users upon which to call for support. I'm not really sure what the answer is, and you're right that ultimately the people developing the code need to validate the documentation.
I certainly think your comments are valid, and any project free or not has to take onboard a certain expectation of customer service levels. Believe it or not as Xavi has alluded to, things have actually improved here! So here's hoping the improvement continues, which leads to the growth of Tiki, which leads to the introduction of new developers, new ideas and a successful project.
For what it's worth I've always found the developers to be helpful when communicating with them on the Tiki IRC channel.