One thing I've never been enthusiastic about has been Markdown's auto-renumbering support. I have never seen someone really being happy with the implementation and lots of people frustrated as they try to embed numbered items and get them renumbered.
1. First
1. Second
Yields:
First
Second
Usually came up on Reddit when someone wants to quote a single item in a numbered list from some external text, quotes only that, and it gets renumbered...and they don't know how to backslash-escape the period to avoid the thing:
1\. First
1\. Second
Yields:
1. First
1. Second
It looks like kbin also does the auto-renumbering. Dunno about lemmy. Kind of the one element of Markdown that I'd be happy to see die. I don't mind having a syntax for auto-numbered lists -- I just don't think that using an actual number as prefix to indicate that that should happen is a reasonable way to go about it.