DCS and Steam variants don't seemingly work together. Check the respective Steam/DCS World stores and there seem to be plenty of warnings about them being mutually incompatible. (This nearly caught me out too!)
I'm pretty happy having DCS getting every penny I spend and not the '70%' Steam sales generate.
NB I don't have a problem with Steam, or any other such 'wrapper', but where I have the choice I quite like to support the devs - I guess the only disadvantage is where games are heavily modded, in which case Steam makes perfect sense.