I would love to debate this, but I have to research a bit of those sources. Specifically about the Rav saying MO is b’dieved. I do believe that MO did save many people from going off the derech in the last few generations though.
I think people look towards the past few generations of MO where many people were ignorant and say “look they don’t follow halacha.” However, many of them never learnt proper halacha (like hilchos shabbos or something) so they keep it the way they know. Today’s generation of MO is much more educated and therefore chooses to follow halacha. They are still MO.
To me, MO is keeping halacha without assering the muttar.