I would say marginally less innovation, not a lot less. There are plenty of Markdown libraries to make implementing it easy, though you are right that this goal of rendering special stuff in your client adds complexity, however small.

I don't want anyone to ***have*** to do that in order to make a client that supports type 1 notes. I just want to speak in markdown to whoever will listen. I don't require an interpreter in everyone's client. My followers on clients that don't have one will either have one in their brain or not care too much, as demonstrated by them still following me.