Also, if something is a good investment, it doesn't mean it is a good investment for a given company.
I worked at a company where annual goals routinely included invest X billion on new technology acquisitions. Some of this money sticks and some doesn't.
It is not impossible, however, to exhaust R&D opportunities with an expected NPV greater than zero.
I have seen a lot of great companies acquired and destroyed by parent companies in another industry.
It certainly can and is often done well, but is not trivial or risk free.
acquisitions in general are all too often vanity projects, rather than synergistic value creators they're purported to be.
Tell that to AAPL: how many projects got cut when Jobs came back to run the company in the 1990s.
Just because you can spend time on something does not mean you should. A company has a finite amount of employess, who have a finite amount of hours of daylight, with competitors nipping at their heels.