While you can't solo you CAN duo.
Which means at most there would be a total of 6 people left stranded, as that's how many level bracket there is. Granted, duoing with two weak players (for the level range) will unlikely be particularly successful, it can be done.
6 is hardly "a lot of people". Thou I guess it can be a significant portion on a dying server.
That said, I would support a second "carry" run if and only if carry run does not count for ranking, not even for the ones who are being carried (for whom it is their first and perhaps only run)