It objectively isn't bothersome, it only takes a handful of keystrokes to export to markdown or to any other format you want.
I am sorry complaining about Org mode's markdown format not being used elsewhere is absurd given how many extensibly options there are for Emacs built in even without adding in anything custom.
No, the org mode file format is the most extensible, open, powerful file format for primarily text based notes ever made. You are simply wrong here, I am sorry.
There are also apps that directly use the org mode file format such as Orgzly, Beorg and Orgro.