Obsidian opens by default loading the last vault I worked on (if I have created at least one).
This is not a very good idea, especially if you often use Obsidian in public.
I feel the need for a dedicated set of options, where one can choose the action when opening. Inspired by the one adopted by Reaper, I would suggest something like this:
WHAT SHOULD OBSIDIAN DO AT STARTUP?
- Open the vault I was working on when I closed it.
- Create a new vault.
- Make me choose which vault to open from those available.
- Present me with these same options and let me choose at the time.