Of course, I can't negate your experience.
But when I look at third party publishers, I see a lot more good then I do bad.
Absolute Tabletop's adventure kits and Dragongrin setting, Sandy Peterson's Cthulu Mythos, Kobold Press's many works, and a huge host of one offs too, such as Graham Ward's Darkplane setting and content expansion, Dice on Ice's Crifoth setting + expansion, Jarl DM's Iskloft setting, the other 4-10 well-made but similar viking settings out there, and so on and so forth.
IT isn't all gathered in one place, so I'll give you that, but when I look at modern 3rd party, I see quality far more then I see unusable drek.