I think you're overstating the lack of quality of the Packers' line. GB has been a playoff team most years since Farve has been there, and they didn't get there by having OLinemen that couldn't block at all. If you look at the post 1980 Cowboys' line, you will see a LOT of older players, and young players who weren't very good. The Cowboys essentially did not have a good draft between Tony Dorsett and Troy Aikman. That's 13 years or so.
My point is that if you don't think Danny White gets to the level of a Marino or Fouts, then there's NO WAY you can take Farve up to the level of a Unitas or Staubach. No way under the sun. At some point you have to consider championships for QBs. Maybe not for kickers, or linebackers, but for sure for QBs.
The only reason that the Pack made it to the playoffs at all was because of Favre. The reason why the team generally could get no farther is that the better teams could exploit the real weaknesses of the Packers at the next level. That is sort of how it was with Buffalo and Jim Kelly or many of the Broncos teams and John Elway. I was at the Broncos/Giants Superbowl and watched the Broncos get blown out in Pasadena. Great quarterback- no help.
My point is that Danny White couldn't do what Favre, Kelly, or Elway did. They were the only reason at all their teams performed at any level for the number of years they did. Put White on those weaker teams and they don't make the playoffs at all.
Just my 2 cents.