I don't know what the design decision is here, but in a sane browser, there should be 0% reliance on "backend servers" in order for it to be usable.
I assume it's just out-of-control polling. The fix is probably to add a stepping timeout on errors. Not ideal, but not a very egregious oversight given that a browser will nearly always be used in an environment that's at least internet-connected.
Lack of internet connectivity should be a basic scenario any browser should have a plan for.