True, but more franchise QBs come from outside the top 10 picks than within, at least as measured by those winning SBs overall (19 of 32 outside 10) and in the last 20 years (8 of 13). Of course, there's more to the NFL than just winning the SB. There are plenty of successful and franchise QBs besides those winning the SB. But I venture to say the averages or trends hold for those as well.
The issue to me is not whether you draft a QB at 1 or 2, but if you give up a ton of draft capital to move up to do it. Of the SB winning QBs that were drafted 1st or 2nd, none the result of the team giving up a bunch of picks to move up to do it - they were all intrinsic picks by the teams that "earned" those picks. Wentz may have been the first, but nothing is given so you can't say Philly would've absolutely still won had Wentz not gotten injured.
I personally think the juries are still out on Goff and Wentz. Things just came together last year for their teams like it did for Baltimore and Flacco, San Fran and Kap, the Cowboys and Dak in 2016. One of the interesting things to watch this year is whether LA and Philly continue their success, or in the case of LA, build on it.