Nothing wrong with building something that turns out to unneeded or doesn't work.
The Bitcoin blueprint is not about efficiency, it's about resiliency.
Only the best ideas & projects will survive. Most will never even get a decent run.
I don't think we should discourage people from following their intuition though. From building what they want to build. We should definitely be careful about how we support them in their building & never support them from altruistic motivations.