These questions are VERY valid and we should REALLY allow them to exist for the following reasons:
.1. These questions usually occur at a very special point in the development cycle: the very beginning.
Why does that matter? It matters because once a decision is made, it will carry out through the whole project and will thereafter be supported.
Take the choice of a JS framework, or a BBS or a CMS. Pick the wrong one for your purposes, and thereafter, you will end up with a series of questions and problems that wouldn't exist if the right tools were used.
Besides, a lot of "How do I do X in Y?" questions are answered by "Use Z". It seems a lot more logical to make more efforts into helping people select the right tools in the first place.
.2. These questions can NOT be answered properly through a Google search.
Google will give you a list of pretty much every product out there, but the real purpose of these questions is not to get just a list.
The goal is to get feedback and opinions on the various products from people who use these products, and which you trust to some degree or another.
Sure, I can type "bulletin board software" in Google and find 20 bulletin boards, all in less than 5 minutes, but Google won't give me the feedback from existing users and won't give me the possibility of asking specific questions that are of particular interest to me.
Also, people giving the feedback here are people which I would have already some opinion of and which I would trust above random strangers (especially those who have already taught me something valuable in their previous answers or questions.
In a sense, questions like these are an indicator of a true community forming, where people feel involved enough to trust other members' advices over those of complete strangers, implicitly.