You see, all the versions are still 1.x in their case.
Steam 'betas' do not support structural differences between versions, nor different sets DLCs.
Should we upload DCS 2.0 with, say, Nevada into Steam as a separate 'beta', it will create
a huge mess for those who will switch between release and alpha version. And this not discussing
the question of which version of Nevada will go into 1.5 Steam installations of those who bought it. And it will.
Also Steam does not support parallel installs of different beta's.
This is really a Pandora's box, believe me.