"But what I know is this..a pilot who is good at flying a C-172, will be good at flying an F-15 and also good at handling a B777..and without wanting to offend anyone, this modern minimum requirement of 500 hours multi-crew, is completely wrong and insane."
Well insane is a bit leftfield. Its not exactly insane if you look at it. They want 500 hours of experience within a multi crew environment.
I think that maybe where you're miss identifying what is valued in the bubble of goods (apart from being cheap and willing. That tops it in today's world). Handling, yes. But modern commercial aviation requires good old CRM amongst a bunch of other stuff that if you study it carefully, single seat fighter ops dont actually give you relevant exposure to.
I don't doubt you're a very competent "handler" of controls being a fighter Pilot. I'm also not not saying you don't have good CRM. You may have fantastic CRM waiting to be used, I don't know you. I've flown with ex fighter guys who equally have good CRM and dire CRM. The same as non fighter guys. It's just your post seems to suggest an assumption that aircraft handling skills are the sole relevance of that particular requirement.