RD believes that the kind of container he proposes is not designed to solve the same broad problems that Linux containers address.
It minimizes the boilerplate of the business logic of the web service and reduces the concepts that the programmer needs to know (eg: when writing a web service, it is very likely that any systemd configuration is just unnecessary boilerplate).
Shell is an interpreted scripting language for invoking Unix programs. It can write conditional statements, loops, it has variables… but unfortunately it has limited capabilities and is difficult to program.
Finally, the RD said that he is not saying that Linux containers are going away, because of course this level of abstraction has its value.
But it’s pretty low-level for most of the “business logic” that developers write. When developers build websites, things like systemd configuration are boilerplate.