According to https://www.telegraph.co.uk/technology/apple/8912714/Apple-i... "An unpatched security flaw in Apple’s iTunes software allowed intelligence agencies and police to hack into users’ computers for more than three years" which sounds serious to me if you're an iTunes user (as I guess many Mac and Windows users are).
But I think the real culprit is that all of the organizations the grandparent poster listed distribute proprietary software which is untrustworthy to begin with. Proprietary malware isn't hard to find (see https://www.gnu.org/proprietary/ for an organized set of links) whether it came with the OS pre-installed on the computer or installed later. So long as it adversely affects the user and leaves the user with no permission to inspect, alter, and share the software (only permission to run the malware) the situation is bad.
