So why didn't any other team pick him up? Performance? The last season (2015) Romo played some games, his passer rating was a 79. He only played in 4 games because his body was breaking down, hence it affected his performance. In 2016, his back broke in preseason, costing him half of the season to heal. He was ready to go by the end of October but this ownership and coaching staff simply didn't and couldn't rely on him. Past performances didn't matter anymore. This was reality here and now. Romo was done. Learn and accept history.
He had horrible luck with injuries. His 2016 preseason injury was a horrible timed slide that resulted in a fracture; how often do you see that happen in the league? The Cowboys made a fantastic decision to have Joseph Randle as the starting RB in 2015 and they didn’t have a back that could pass protect. What do you get? Two collarbone fractures. Yeah, Romo didn’t want to win but he came back midseason earlier than he should have to help a 3-7 team fight for a late season run. If Romo comes back and plays against GB in the playoffs, he absolutely wins that game.
Another team didn't pick him up because he retired. Injuries did catch up, but it wasn't because he couldn't be efficient on the field; he couldn't stay on the field, period.
79 QB rating in 2015? Seriously? The 3-1 record? Let's go over it game by game:
Week 1 VS NYG led a game-winning drive
Week 2 @ PHI: fractured collarbone
Week whatever VS MIA: first game back after the fracture and had a mid 80s QB rating, but was a big reason why they won the game
Thanksgiving VS CAR on a short week: horrible performance, re-breaks collarbone and QB rating of 27.2 (the main reason for the 79.1 QB rating)
You can spin it any way you want, but Romo carried the franchise for years when Dallas did NOT have a top OL or mid tier defense, something Dak has had for the majority of his career.