50% of the qbs that are still playing were not taken in the first round.
List all the franchise QBs right now (aka the QBs teams feel like they can contend with so no Davis Mills who is clearly a transition QB): Mahomes, Herbert, Carr, Allen, Tua, Burrow, Jackson, Watson, Lawrence, Hurts, Dak, Stafford, Murray, Cousins, Rodgers, and Brady. Then you have guys who have small asterisk aka guys who might be: Geno Smith, Mac Jones, Daniel Jones, Goff, Tannehill, and then Mr. Irrelevant. Could also talk about Russell Wilson who is a franchise guy by force. Every other starting QB teams are actively looking to move on from (the Raiders are moving on from Carr but he will absolutely be starting somewhere for a team that thinks they are a QB away).
Now with that list go ahead and tell me the draft positions of the QBs in question. Of the 16 guys I put on the franchise list 13 are 1st round picks with overwhelming majority being high 1st round picks. Even in the second list of asterisk guys only 2 were non first round QBs. Basically you can find a backup level QB who was not drafted in the first round but if you want a franchise QB you look to the 1st round and generally high in the first round.