Maybe ST is an exception. In my experience, TI (E2E), Microchip, and Analog Devices (Engineer Zone) have excellent forums and provide spot-on information. Since Jorge participates at Autodesk (whatever its forum is called), I suspect the Eagle part is well supported too. (I haven't visited that forum.)
Now, if you want cartoons from YT and FB, hand holding, how to crack security, how to solder, what oscilloscope to buy, and so forth, they are probably the wrong place.
In terms of activity, they are nowhere nearly as active as EEVBlog, so I check in every few days at Microchip. Waste a lot less time there too.
One might compare manufacturers' forums to libraries and more social blogs to 24/7 news channels.