ARC is a mess. eARC makes it less so in that you do not have to activate HDMI-CEC to get audio return as you do with ARC. So, devices connected directly to the TV can have their audio sent unchanged to the AVR via eARC provided the TV and AVR are both capable of the feature. If one is using their Smart TV apps and does not have other streaming devices, audio return via ARC/eARC makes sense so that their audio is not down mixed via the optical output since some apps are streaming in DD+/Atmos. But, ARC/eARC and Optical will not always get you DD 5.1 if the TV app only sends DD 2.0. With TVs dropping DTS, I do not think the TV will pass a DTS track along to the AVR from an external device. I use ARC but am having more issues with it lately. Still, it is nice to use the TV remote control for everything via HDMI-CEC in combination with its universal remote control function and have it switch the AVR to the proper input when I want to watch another device. I think many people find there aren't enough HDMI inputs on their TV for all of their devices and many new TVs use composite break out connectors for older analog devices. To each his own. Read those manuals and make sure the way you want to hook things up gets you the picture, sound and convenience you desire.