So,
Safari crashes with a whole lot of state (opened web pages, tabs, etc). No problem! After you restart it, you click on "reopen all windows from last session" ... except it doesn't work properly!
The URL that a given window is trying to open is not placed in the URL window, so that if the open fails, you have no way to hit "reload" for it.
Bazillions of "untitled" windows for which you have no idea whether that was a real window, or ... not.
The "activity" list is even worse - an additional "untitled" window for every window, again, no attempted URL data.
Just guessing, but I bet Safari isn't being polite to the sites where multiple windows were open either, i.e. reopen them one at a time, serially.
GRRRRR!