If the idea guy isn't the developer they have to be the sales and marketing person. So if they have great ideas and can sell them and get money in the door then I'm happy to work with them.
1. "Idea guy" comes up with ideas faster than any human being, or team of human beings, could implement them.
2. "Idea guy" gets frustrated because it takes team so long "just to add a button or two" or whatever, and the relationship often sours. Of course, this responsibility may fall on engineers as well, because they fail to realize that communicating engineering issues to non-engineers is an essential part of their job... or they're simply bad at it.
Coming up with ideas is easy.
Understanding end-users and coming up with (non-incremental) ideas to genuinely help them is difficult and is a fairly rare talent.
Coming up with such ideas in harmony with the engineering+logistical aspects of bringing those ideas to market is unicorn territory, and those people are super valuable.
10 years ago, I was the "idea guy" managing a team of non-developers. I grew frustrated with the pace of bug fixes and (what I considered) small improvements out of the development team. I got so frustrated that I started developing my own applications for my team, which greatly increased their productivity. Eventually that led to my career as a software developer. Years later as a CIO, I am frequently asked by the idea guys, "Can't you just build this one little thing?" and I get to be the guy who says "well that's probably a 3-6 month project." Invariably the idea guy starts to think that you're intentionally sandbagging him and sours the relationship. That and some other things ended up driving my predecessor to burn out, which is how I became the CIO.