The point of containers is to make updateability easy. To bring embedded software closer in line with what's going on in the cloud. To enable the kinds of workflows we have had in every other part of the development world for decades. It may or may not be right for your project. So long as you understand the intention and make informed choices about the tradeoffs, there will always be cases that fall in the one or the other side of the fence. I don't perceive this as being a dick, you're stating a reasonable case for a model that does indeed work for a lot of cases.
We will continue working to reduce overhead, hopefully power requirements and cost will go down, and somewhere along the curve, we may even meet your needs at some point. Whatever the case, we're pretty sure we'll never cover everything so if we gave the impression that resinOS will end all embedded OSes, then it was the wrong impression to give. :)