This doesn't seem like a big deal to me. Basically Dolby is saying that if you have a device that decodes a dolby input, you can only upmix it using dolby atmos not a competing upmixer. This works out great for me as I find the dolby upmixer to be the best anyway.
Video: JVC RS4500 135" ST130 G4 screen in batcave, htpc nvidia 1080ti madVR.
Audio: Anthem mrx720 running 7.1.4, McIntosh MC-303, MC-152, B&W 802d3 LR, B&W HTM1D3 center, B&W 805d3 surround, B&W 702S2 rear, B&W 706s2 x 4 shelf mounted for atmos, Infinite Baffle Subs 4x15 fi audio running on behringer ep4000 + 2x12 fi audio mounted in main chair firing into back.