I agree that hardware is hard. But radio hams have been building hardware, and sharing designs, for longer than software has existed. A large part of their success is about the mindset. A professional RF engineer will demand a certain set of instruments to make their job possible. A ham will either find a way to make the tests with cheaper equipment, or find a way to build the instrument first (see, for example, the various homebrew network analyser projects). Partly this means relaxing design specs to make a project more likely to work. Partly it means recognising that building one of something is different to building 10,000 - if your project takes time spent at the bench tweaking individual components, well, that's part of the game.
If you come from a professional background, open source hardware looks impossible. But if you add a little more ingenuity, and pick your projects carefully, it's entirely possible and can produce some very impressive projects.