I was so excited when I saw that Ello uses Markdown!
That is, until I found out that Ello doesn't use Markdown. It simply happens to render a few constructs in the same way that Markdown does (e.g. lists, bold, italic, strikethrough, etc) but leaves out a number of things from the already-minimal markup language (e.g. block quote text, images, reference links and surely more...images?).
So now we have yet another custom, roll-your-own flavor of Markdown, each of which, by their very existence and inconsistency with each other, reduce the usefulness of ALL Markdown flavors. It's a fantastic way to destroy a beautifully simple standard.
To Ello's credit, this is the first Markdown variant I've seen that's actually LESS useful than Markdown itself. Way to go, team...