But adding a toast isn't free. It's a distraction, and arguably a pretty intense one for ND folks -- especially when it becomes a standardized message center with multiple items queued up.
In many cases the most useful toasts would also be better if they weren't toasts. For me, the most useful toast I interact with also demonstrates why toasts are bad UX: creating a new ticket in Jira. Since that can't happen instantly, it needs a delayed message to let you know when the ticket is created and you actually have a URL to open. A toast is useful in this case, but it's also far from optimal, because for some reason it's going to disappear in a few seconds, and it also won't tell me how many seconds I have left to read it.
Why would distraction be the primary mechanism? We figured out decades ago how to put a button in the header that opens a messages feed which the user can read and dismiss at will. While it's possible to implement such a feed badly so that it's annoying, it's difficult to implement toasts in a way that aren't annoying. Maybe even impossible.
