I remember the first time I saw that insert it was a colour photocopy my first trade partner sent to me to show me some of the ponies the US had way back in the internetty dark ages of the 1990s. I immediately became obsessed with the pearly baby unicorns. I also wonder about Baby M's name. I wonder if it was an error in their recollections or an issue with the licencing for Moondancer at that point.
Inserts are awesome, always great to see them.
We never had any exclusively MO ponies in the UK bar Lucky and the Embers, so I'm sort of glad we never had those inserts as a kid. It was bad enough Hasbro teased us with the early unicorns and pegasus ponies. I can't imagine growing up obsessed with Rapunzel and then as a collector seeing her price tag.