Nice link here summarising the limitations of Atmos via HDMI-ARC connection
https://community.cedia.net/blogs/david-meyer/2018/06/25/dolby-atmos-over-hdmi-arc
while E-AC-3 can support up to 15.1 channels of audio, it's well beyond the HDMI ARC spec. Even getting 7.1 channels to pass is a stretch, so even if the stream contains object metadata, it will lack the resolution and height speakers.
This seems to clarify what my ears have been telling me over the past few days, compressed Atmos in a DD+ stream just sounds too overly processed and is lacking clarity.