This is true. I have the dometic that uses the digital comms.
I ran into the same issue in my home (Honeywell). Can't use a smart thermostat unless I pull both parts out.
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2016 RAM 3500 DRW 4x4 LB LoneStar Edition, w/Timbrens, Andersen Ultimate 2, Swift Hitch SH04 WiFi Backup/Rear View Camera
2018 Chaparral 360IBL w/Tireminder SMART TPMS, Furrion Wireless Observation System, Progressive EMS-HW50C
2006 RAM 3500 DRW LoneStar Edition
2011 Starcraft 392BHU w/Andersen No-Sway hitch