I can't recall anyone "pushing" corny kegs.
I'm not even tempted to try sankes, simply because what I have works terrifically, so what's the point?
There are reasons NOT to use sanke kegs.
Here's one: can't be easily stacked.
Here's another: Don't come in small sizes like 1.5, 2, 3 gallons.
Here's another: aren't readily available used at cheaper prices like corny kegs are available.
Here's another: can't be as easily sprayed out as corny kegs.
Here's another: new, they're more expensive than Torpedo kegs made of the same stuff.
Here's another: to switch requires changing the QDs to a sanke connector, costing more money.
Here's another: they don't come in two 5-gallon form factors, i.e., pin lock and ball lock. Torpedoes come in both form factors (and both are ball-lock connectors), which means the shorter ones will fit on my keezer's compressor hump while the taller style of the sanke keg, w/ connector, will not. According to
http://www.beveragefactory.com/draftbeer/home_brew/kegs/KEG-165G-D_threaded_D_valve_keg.html the height is 23.25" and the D coupler and beer line will add 5.5" for a total of 28.75". Too tall.
Here's another: they're heavier than corny kegs according to this source here at Beverage Factory:
http://www.beveragefactory.com/draftbeer/home_brew/kegs/KEG-165G-D_threaded_D_valve_keg.html If the "Specifications" tab is correct, they weigh....27.75 pounds empty. It's not that fun to lift a full corny keg into my keezer; can't imagine why I'd want to add another 20+ pounds.
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In short, Johnny, while you may feel they are superior there are clearly reasons--good reasons, rational reasons, fiscal reasons--for people to prefer corny kegs over sanke kegs.
In fact, when I look back over the list above, I wonder why anyone would even consider sanke kegs. Don't you?