As an example, SCO own copyright to various pieces of Linux. Microsoft could buy one of the
small companies that owns various files. Stepping into obvious legal uncertainty like this
would allow for the generation of huge quantities of FUD ("Linux violates its own copyright
license. Do you really trust that it doesn't violate others?"), DMCA takedowns and lawsuits.
Paranoid? Yes. But no major Linux vendor is going to leave themselves open to that for the
sake of a single feature, no matter how attractive it is.