Most of this mis-information comes from flying schools that are out to make an extra buck. There is nothing to stop you from going straight from RA-Aus RPC to PPL in very limited hours, like <5. Pilots have been doing this for years. I know a pilot that got his full PPL with CTA without having ever gone solo in a GA aircraft. It's all about the school and how much they wish to bleed you of your hard earned. (Unless you are a slow leaner of course)
I recently became aware of a high profile dual RA-Aus / GA school that is deliberately going out of their way to NOT inform RPC holders about the RA-Aus nav endorsement. They are telling students that the next step is to get an RPL and as a result selling them additional training for that license and subsequent navs to follow, at the higher GA hire rate.
Said company amongst others are also heavily into well-worded packages on their websites that make it sound like you get the works, but not telling you how much extra to make it a value meal with fries and coke and toy.