This is false. The presence of player graphics is enough to disprove it. Also, Combat was co-designed with the console so if anything it's a Combat machine (but even that isn't quite true. It was designed to play multiple, advanced (at the time) games.
The Atari 2600 is designed to be a pong machine.
I've read all docs and nothing suggests it's a pong machine. Someone later may have incorrectly inferred this though.
If you read the documentation(Atari-age), then you might understand how this machine was designed and why I stated it is designed as a pong machine.
Halo 2600 did not pioneer this technique. The earliest known use of this was around 1983 for an unreleased prototype. Also, batari Basic kernels have been using it since 2005.
I think this system had to be the most exploited system out there. For example, the high resolution 6 digit scoring system. The 12 digits letters and numbers text using alternating lines. Now just recent, Halo 2600, discovered early HMOVE to remove the pisky black line that is on the left side. HMOVE is used to reposition sprite.