A Squared, when I got here in the early 90s, aircraft had a little A5 booklet thingy that had replaced the POH, it had some take off and landing charts (different to the manufacturer's, eg those boxy things for Cessnas instead of the manufacturer's tables, which
AFAIK are STILL in the PPL exam!) and told you where the green arcs were on the T's and P's gauges. The rest of the pages were usually missing. If you were lucky it had the weight schedule and some strange Australian version of the loading charts. It had none of the standard layout of a POH and no useful information on the aircraft systems or normal operating procedures but (I was told) had superceded the POH.
I'm sure there is someone here who was around when they were introduced and can tell us what the reason, apart from the Australian necessity to reinvent perfectly good wheels, was for these things?