You can't enter isolation mode when nothing is selected
Sometimes I want to create artwork without messing up with existing one, and without locking/hiding anything (because it's require for other operations).
Sane way is to enter isolation mode and start there.
But NO, AI won't let you isolate empty space! And I have to create one thing (trying to not auto-connect to existing paths), then isolate it and finally draw in peace.
If you afraid that many users will double-click nothing and struggle understanding what has happened, make it an option.

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Graffix offers a ToolShed plugin that allow to isolate 'nothing' (along with other additional features):
https://rj-graffix.com/toolshed-adds-isolation-menu-items/ -
Matt Phillips commented
just make a single point, right click, and then select Isolate Selected Path.