> No rational company is going to create useless projects just to retain expensive engineers. What's the point in retaining engineers if you're just going to pay them to work on something without expected ROI?
(Short) story time!
Windows on ARM was a solo pet project of a high level engineer at Microsoft!
There are some engineers who are so valuable that letting them spend non-trivial amounts of time on whatever they want is a very good use of company resources.
Sometimes just not letting the competition have them is valuable!
I've worked with a few 10x-20x engineers, if someone is that productive, they can spend 2 years off on another non-ROI project, come back, and spend 2 years on a project with ROI, and the company still comes out ahead.
Most company's aren't smart enough to figure this out, then again determining who these people are is also a problem. That latter part is funny (ironic?), because on the ground floor everyone who encounters a world class engineer is pretty darn sure of it.