I don't even like carrying a wallet around these days unless I have to. I don't want to carry 2 more objects on top of that.

Plus I forget my grocery list half the time but never forget my phone.

I only use Postit notes when I'm at the desk strictly for stuff I need to do around it.

Open the notes app on the phone and type your list? Do you need another app for todo items?

That's a good point, I never fully learned Notes. I just like using markdown writing longform stuff and the simplicity of a dedicated todo interface with shortcuts to quickly add them w/ dates etc.

I use both. But I can't share and collaborate on both easily.

There are multiple collaborative text editors and document apps.

I'm pretty sure this is for simple sharing of probably very ephemeral lists like a shopping list, vacation list, etc. If you got the link, you got the list. I don't think this is meant to replace reminders/tasks apps on android or iPhone