What would make you partner with someone non-technical?

I have worked with people with marketing/sales background and people managers who have engineering degrees but mediocre engineering skills.

My conclusion is I should avoid working with them again. One typical problem with them is that it is difficult to build trust. They have no sense of how long implementation would take and they don't trust your estimate. They think you are lazy. They tend to over simplify things, and command others on a very high level like a king (like "grow the economy"), leaving you to figure out all the details and also take the blame if you can't do everything in 2 days. They hate engineers, because everyone else is a cheerleader, only the engineers are nay sayers.

For my own health, if I ever start a company again, I'd only work with good technical people and only serve the tech market (even that means missing on other profitable opportunities).

Someone who can handle the marketing / sales side.

Relatively, technology is easy compared to the human behavior stuff (e.g., Marketing).

If they can think strategically about the product, the market, and how to compete now and in the future.

Also if they think about the business model as enabled by our product and dynamics within the marketplace, versus viewing things from an adversarial perspective.

Sales - just pick up the phone and dial

UI/Ux design

Visual design

Marketing