A lot might depend on the type of standby ADI/AI. The old electromechanical displays are indeed not easy to read and fly if not trained so. The newer PFD-style LCD displays are much easier to use. There is no parallax error to begin with and the display is very familiar as it is nearly the same as the "big" PFD. Those i know do not offer a FD, however they do an ILS/BC approach display if desired.
Raw data flying has something to do with it of course as it offers a cheap training in scanning, hand to eye coordination and building up of muscle memory not to mention the application of simple pitch and power technique. If one is not used to raw data flying and not trained on the standby AI the results will not be pretty, as displayed in this case.