OP doesn't actually identify what is problematic with the toasts! The `The Problems with the YouTube Toast` section merely describes what OP sees, not what is bothersome to OP. I'm guessing that the issue is all the different locations on the page where things happen: the control, the dialog, and the toast are all over the place, thus maybe that is distracting to OP. In that case the issue is about UI element placing, not really about the toasts.
Toasts help communicate that an operation completed asynchronously after giving control back to the user without making them wait in a modal dialog. This is a very good UI/UX, especially now that users are trained to understand that asynchrony.
While I'm in favour of asynchronous feedback like this, placing toasts nowhere near the button you've clicked is confusing when you get to bigger monitors. A toast in the bottom left on a large, widescreen 4k monitor can literally be half a meter away from the place you clicked, so the toast might as well not have been there. I myself have lost the progress notification for a file copy in KDE because it was placed all the way in the bottom right corner, and my screen isn't even _that_ big.
A little popover near the button makes more sense. Or, in this case, simply disabling the checkbox until the asynchronous action has completed, and using the non-disabled state to indicate success (or show a useful error message when the operation fails).
Right, so the issue is placement, not really toasts. I would prefer the pop-over you mention to toasts, but I definitely don't want to lose asynchrony.
Toasts help communicate that an operation completed asynchronously after giving control back to the user without making them wait in a modal dialog. This is a very good UI/UX, especially now that users are trained to understand that asynchrony.