Yes, thats part of the issue. I was interviewed once by an university student who was working on a navigation system for blind pedestrians. The idea is great, of course, but it was obvious after a while that primary mtoivation to work on this was to make progress in her academic career, i.e. get a grade for the project. "Having" to work with potential end-users was part of the story, but not priority :-)

Also, imagine how the dynamics of such a project works. There is the initial idea, paired with a lot of enthusiasm. Suppose thats all, but the idea itself is not practical, at least not with the planned approach. Now, this team finds/hires a "consultant" who is blind. In reality, they will enthusiastically tell you about their idea, and almost always assume you are going to get them feedback without expecting any compensation for your work, because ', you know, having a self-interest in such a project must be enough for the blind man to be happy... That aside, what is their "consultant" going to tell them. Are they going to be straight upfront and say "that is sweet, but totally inpractical", or are they going to tone their analysis down a bit, because they dont want to see these nicely-motivated people fail? Also, if the "consultant" treally tells 'em its a bonkers idea, are they going to believe it, or are they perhaps more convinced of their initial plan still? These are things that are going to happen / already happened in the past...