I don't believe Eli Manning should be a first ballot hall of famer. Strawman argument. Should get in, but not the first time he's eligible. He wasn't the all-time great quarterback his big brother was.
So the Chargers had great teams, playoff worthy, but your position is that Rivers held them back? It's not Rivers' fault that an incompetent organization couldn't build better teams around him. He was one starter out of 22. If Josh Allen continues playing the way he is for another half dozen years or more but the Bills never win a Super Bowl, does that mean he isn't a first ballot Hall of Famer?
Philip Rivers did as much with what he had to work with as any quarterback ever has. He was outstanding year after year, as good as it gets. He was an all-time great, indisputably. I've been watching the NFL for many years and Rivers is up there with Peyton Manning, Drew Brees, Tom Brady, Brett Favre, Steve Young and possibly one or two others as the best quarterbacks of my lifetime, one I went out of my way to watch. I marveled at how good he was.
BTW, "zero playoff resume" is ********. Rivers had a 134-106 record as a starter. He led the Chargers to the playoffs six times and the Colts once. He had a 5-7 record in playoffs, making it to the AFC conference championship in 2007. Again, I watched those Chargers teams, and just like Big Ben put the Steelers on his shoulders for many years while Mike "He's Never Had a Losing Season" Tomlin got a disproportionate amount of the acclaim, Rivers did the same with the Chargers year after year. First ballot Hall of Famer without question.