RTS is definitely and arms race, but I don't see it as repetitive. TONS of strategies to use/create. Take TA for example.
Gordon liked air and would create kill zones for ground troops.
I liked ground attacks and figuring out ways through kill zones.
Leisher hoped we would ignore him till he could launch nukes.
3 different ways to play.
Then the next game, I'd create more air defense because Gordon's stuff damaged key infrastructure last game. And might go all air just because.
Gordon would increase artillery range.
Leisher hoped we would ignore him till he could launch nukes.
You can turtle and go full defense and production early and go for the big units.
Not knowing what your enemy is doing forces you to think/change how you use your resources.
Repetitive? I strongly disagree!
That being said, this is one of the problems I had with PA. There was only one set of units. I felt totally ripped off supporting it's kickstarter and then finding out there weren't going to be factions/races. We all play with the same few units. This, to me, did lead to some repetitiveness. What you could do was limited to the few units we could play with.
And when I said I would load TA in an earlier post, I meant PA.