A scientist who was pursuing some research was looking at his results and trying hard to come up with practical applications for it. Richard Feynman, coming across him, asked him why he was trying so hard when there wasn't any practical application for that research. And his response was, "If I can't think of anything, then they won't fund my research."

Feynman goes on to point out how scientists end up trying to justify their research just so they can get funding for it rather than actually go after the problems and applications that do get funded. Of course, this is because those real problems are actually a lot harder.

This is the case with startups as well. And with ideas within companies. People just end up finding ways to justify why they need to do something for the fear of not being allowed to do it without that justification. So, they cook up seemingly plausible but flimsy justifications for why they want to pursue something.

This mainly comes out of the fear that if what they are working on is useless, will they get to work on something else that is useful? Or will they instead have to shut shop and look for another job?

Companies like Facebook and Google enable their employees to work without this kind of a fear. As a result, they end up doing far more interesting things than most others.