I like synthetic oils quite a bit, there are lots of advantages to them.
But any conventional API-SN rated oil is most certainly not junk. The overwhelming majority of engines today will outlast the rest of the vehicle by following the manufacturer's scheduled maintenance with conventional oil. One example that comes to mind is the guy in the EcoBoost forum with over 300,000 miles on his 2011 F150. Oil changes with conventional Valvoline every 6-8,000 miles and he's never had an engine problem.
Cold start performance, ability to keep engine parts clean, and the ability to run longer drain intervals are all great reasons to choose synthetic over conventional. The idea that your engine will fail early with conventional isn't, that's never proven to be true.
His: 2015 F-150 XLT Crew, 3.5L EcoBoost
Hers: 2015 T-350 LWB LR wagon, 3.7L V6