Just to be totally pedantic about it, in a nice way <lol> Every file
on a Windows system is executable ( proof of this is using Linux to
view a Windows HD and checking file permissions, even a simple text
file has the executable bit set ! ) and the extension is a flag to
tell Windows what it's supposed to do with the file when it runs.
Hence the ability to make it try to open something with the wrong
program - i.e. rename an EXE to JPG and it will try to view it as a
picture. Linux would not be fooled by this :-)

Part of the security issues with Windows is this executable property
of every file but to change that would mean a total re-write of the
kernel and that's not going to happen as every program that runs on
Windows would have to be re-written too !