portfolio margining does what I describe and has a regulatory minimum of $125,000 or so net liquidation value (portfolio size), SPAN margining can as well which is what the futures and futures options market uses at any portfolio size
so yes individuals can access both
the primary benefits are cross margining, using other assets to fulfill or calculate margin requirements for a new position
and portfolio margin requirements are easy to calculate, just take the loss at a 15% move and whatever that loss is becomes your current margin requirement, it is a 6% move for indexes (like S&P)
the way to get in trouble is by confusing the margining system and hiding exposure behind synthetic positions (example, a combination of derivatives to make it look like you are long stock)
so yes individuals can access both
the primary benefits are cross margining, using other assets to fulfill or calculate margin requirements for a new position
and portfolio margin requirements are easy to calculate, just take the loss at a 15% move and whatever that loss is becomes your current margin requirement, it is a 6% move for indexes (like S&P)
the way to get in trouble is by confusing the margining system and hiding exposure behind synthetic positions (example, a combination of derivatives to make it look like you are long stock)