I can't recall all the detail, a large chunk of it bolied down to; having a proven track record, a device to show to ODM's in a working state, & to showcase the full potential of the sw.
Also IIRC one of the factors was that they wanted to ensure they had a regular revenue stream, they couldn't take the risk of relying solely on wealthy backers/loans etc.
And IIRC the original intent wasn't necessarily for it to be a definite long term thing, but after a short time it became that, as they saw so many inherent benefits...

They've detailed several times why it was important to them, & why it wasn't as simple as saying: Here, take our license for this sw & you -largely- take care of the hw & sell the end product.
That would've been their preference, as they saw themselves (& still primarily do) 1st & foremost as a sw co, but they determined it wasn't going to work -entirely- that way, for them.
To move forward they had to have device(s) in the game too, I remember vociferously arguing against it in the earliest days, I didn't get it, they explained a lot back then & thereafter.
Too bad I don't have a photographic memory, just CBF'd trying to find it in that last post (nor now), perhaps stskeeps will fill-in-the-gaps/refresh-our-collective-memories...

@stskeeps, I don't suppose you can flesh-this-out with lots more detail?
Update: He refuses to, oh well, if they want misinfo/misunderstanding around this subject to perpetuate, that's their problem.