It is not done in "purpose", the virus spreads itself into any non-updated OS.
I find troubling that healthcare establishments are not updating their legal Windows versions.

OFC, the affected versions of windows are mostly, pirated, with no available updates. So, I am wondering if perhaps (and only "perhaps"): Isn't microsoft behind all this as a "you better BUY your OS, because pirating it may become more expensive for you".