It's all subjective how far you're going to delve into it, but Discovery was a science vessel before the Klingon war, so the argument is that it is much newer than the rest of the ships in the fleet, and the TOS Enterprise has been in service for many years already. It doesn't really bother me
that much that they somehow have holographic communications and battle simulations. If the show sucked I would be more apt to point out these seemingly irreversible errors... But the way they left the cliff-hanger I wouldn't be totally shocked if Discovery was never heard from again!
I wouldn't put much past the writers, as they really are full of surprises. Which is great I think. Trek's story-telling needed an overhaul, and I think it finally has a good one.