I really doubt Toyota has some gasket making factory hidden deep in the mountians, "Mount Toyota". I'm willing to bet that they have a contract with other gasket makers to make gaskets for them. Like Felpro and others. Felpro is huge, why would they purposely make bad Toyota gaskets. I'm no gasket guru I doubt they make bad stuff.
I used an off brand on my car, so far so good except for the valve covers, they are just barely leaking.
Again, I'm no expert, but that my personal belive,experience and my five cents..:icon_neut