By controlling the Windows ecosystem they could "disrupt" any competitors trying to produce applications, pushing Office while alternatives struggled, and they could use Office to push Windows.
Charging OEMs a flat "per-CPU" fee for licensing meant that Microsoft was getting paid regardless of the OS being shipped on the system. They eventually had to stop doing this, but came up with other ways of achieving the same effect.
There's no Office for game consoles. No matter how popular your title is, another platform will have an exclusive of their own that's just as compelling. They can't strong-arm OEMs because they are the one making and selling the hardware.
Linux has all the technology needed to overcome Windows, lacking only fit and finish.