Mass market, yes. But Herzog Zwei for Megadrive was out earlier and was already a RTS. It was not very good (at least my memories of it are not good - playing with a gamepad was a nightmare) but it was already going in that trench.
1) The player fulfills the commander role by directly controlling a unit on the battlefield, not in "god mode". The commander unit isn't merely a stylized cursor; it also directly engages in combat.
2) No base-building or tech tree. The number, location, and capabilities of all bases are fixed.
3) No explicit resource gathering. Money is automatically accumulated based on how many bases you control.
It's arguably closer to a MOBA than an RTS.
Most of the successful games that copied Dune 2's format were written by the same studios (Westwood for the C&C franchise, Blizzard for *Craft).