It’s not, though. It’s a much wider potential for failure, as there are a great number of dependencies that are often left to individual developers to maintain. That may be a somewhat reasonable amount of risk when you’ve got multiple options for dependencies and no major target, but when the entire EU relies on single individual maintainers? That’s a massively exploitable threat vector. It would be absurd to assume no one will take advantage given what we’ve already seen.
It would be an extremely foolish move to put the whole EU’s security on one single set of open source dependencies. Microsoft at least has a financial and legal incentive to try to prevent straight up breaches by state actors, shitty as they may be. There’s no such resource allocation or responsibility when it comes to open source repos.
Push a switch to Linux, by all means, but security monoculture is as big a mistake as putting your eggs in any other single basket, especially one as exposed as one single distro.
There’s a world of difference between interconnectedness and an enforced monoculture of dependencies on a wide range of insecure repos maintained by hobbyists.