There has only been 2 all rookie final 3's. Both being seasons with all rookies.
Survivor 22, 23, 25, 26, and possibly.... lol 27 have all had a veteran make it to the end.
Let me remind you since Season 21 there has been 115 total rookie players.
There has been 32 veteran returnees. (16 of these returnees counted as apart of the 115 rookie players from seasons 21-27)
By the end of this season possibly 8 returnees will have made the final tribal council. While only 13 rookies out of a possible 27 rookies made the final tribal council since Season 21.
There has only been 2 all rookie final 3's. Both being seasons with all rookies.