Mark started the thread, and is assuming the IP/IS "worldview" as a premise:
- IP/IS is fundamental and necessary to truly effective budo.
- Certain historical "greats" had it.
- They didn't or couldn't successfully pass it on.
- Almost all current-day aikido is missing it.
- It is in the process of making a resurgence in certain circles.
Whether you agree or don't (I don't), OP holds this worldview and is framing the discussion within it. I think that arguing against this is worldview off topic for this thread.
If someone has a proposition they want to prove, for example, that lots of solo training for aiki-pee leads one to be a kinder, gentler type of antisocial crazy person, then this person would lay out their assumptions and show how they lead to his conclusion.
It is then part of the normal process of logical discourse to examine the premises of the argument and argue for or against them.
Part of that involves challenging the unstated assumptions, such as come with a "worldview." Subjective experiences that are fervently believed to be objective fact are fair game.