If you read my comment carefully, you will see I mentioned "provide decent directional experience". Bars like Jbl Bar 9.1 or LG SN11RG or Samsung Q90r etc come with dedicated surround/sattelite speakers, upfiring atmos speakers and decent subwoofers to provide a decent surround/atmos experience for people who can not setup a dedicated surround setup for whatever reasons. Yes, I agree that they won't match the quality of a dedicated setup costing twice as much, but dismissing them altogether without even giving them a fair chance is a bold move, I would say. While 50k Dolby Vision TVs are ill equipped to produce Dolby Vision, mid-high end soundbars have come a long way from their early days and can be considered a viable alternative for space constrained setups.
In short, saying eARC is useless, is again a bold statement. Might be useless for your specific case, but not for everyone else.