Hardware start-ups can often benefit from a hardware accelerator that puts in $100K-$250K for 10% equity. Usually that early seed round would get a startup to a sellable MVP that they can launch on a crowdfunding site. Hardware is often much more expensive to build than software, so many of the incubators that only provide $20K or so won't get you to an MVP.
Yes, VCs do look for validation before investing, but it can be validation that came from any previous seed / angel round, not necessarily a crowd-funding campaign. That validation always comes in the form of traction or revenue. Of course crowdfunding can be a great, cheap, market channel that helps you acquire early adopters.