That was more because Tomulsa and him never synched and latter Gabbert on paper fitted Chip's offense better. But when Gabbart proved he was horrible CK started the rest of the way. But even that really doesn't disprove that he was a better than average qb. I mean if you want to try that then you would have to convince me that Flacco isn't better than close to half the starters in the NFL because he got benched.
In 2016 there were atleast 15 starters that CK was better than. In 2017 I would say it was about the same, but even then he was atleast the best backup available.
While I give him the credit of having 2 solid years and leading his team to 1 SB and 2 NFCCGs, he was only slightly better than average. Usually that gets you a job, but his protest was not standing for the National Anthem... Well here is the thing, the NFL has a huge deal with the DOD, and that is the reason why everybody is out on the field during the NA. Ever wondered why the NFL PA announcers phrase it " Please rise, and honor America and the troops abroad" during NFL games and not college games? Budweiser also has a huge deal with DOD and the NFL. If DOD ever pull out because they felt the NFL was endorsing CK then the NFL could potentially lose its two biggest sponsors in one day. So the fear of losing sponsorships is probably the driving reason. If Tom Brady, Aaron Rodgers, Drew Brees, or Patrick Mahommes did it then they wouldn't fear not having a job next year.
I think there is some truth in that.