Not clear who you are replying to. I didn't ask for slash - not part of markdown but a UI feature.
I think that there is a common enough core for markdown for the devs to be able to satisfy the requirement but I recognise one cannot satisfy all of the people all of the time. Academia seems to have embraced markdown well enough for sharing of technical papers (especially including Python and R code, as well as general content, in Jupyter Notebooks).
It seems most of the people on this post asking for markdown want it as a native format standard, preferably as an option over the long-standing format but otherwise (and also) as an option for document attachments with full preview and edit support.
I recognise the challenge of having built a product on a base format, xhtml, and not wanting to support round-tripping. However, using markdown purely for rapid text entry (lightly supported on the web interface I believe) is possibly useful for some but I expect that would frustrate most experienced markdown users who generally want to be able to focus on rapid note content entry and edit rather than formatting. When I am in note taking mode, I don't want to take my fingers away from main keys to mess with control/command-somekey or menu clicks, it breaks my flow. Markdown is like (X)HTML rather than CSS in this regard.
I and the various teams I am in are not about to cancel our Evernote subscriptions. I value the product for its many features and have not yet found an alternative that fills my use cases despite the markdown frustration. I have looked and will continue to look though.
My experience of using the md file attachment approach, not having a good preview and having to use an alternative editor is not ideal. For me, it somewhat undermines the key note taking focus that I think Evernote has at its core and which is certainly central to be usage.