We're human beings. For the best of us, 90% of the conversations and thoughts we have are junk and most of us are worse than that.
Always has been. Probably always will be.
Expecting any internet community to put out more than 10% of good content is an exercise in futility. The only reason why it seemed so much more engrossing and interesting when you arrived on the scene is that you had not acclimated to the room yet, and you were consuming the best, easiest to acquire thought morsels that the community had scrounged out of the trough and recycled until it could stand the test of time within that community.
Then, once you have consumed that bit of the best, you think the rest would be like that as well but instead you find yourself in a room full of people who all know the same things and think similar thoughts, and you season along with them, getting the better secondary and tertiary thought morsels, and maybe contributing some yourself. And then, finally, you see bright fresh faces coming in, following the same trail you followed, coming to the same wrong conclusions you came to, and you think, "There goes the neighborhood" and tell yourself how good it used to be when you were ignorant and didn't know any better.
Eventually you reach the next point, which is realizing that it was always like this. You just didn't know any better. Now you know better, and you also know there is nothing you can do about it. You can stay and help others enjoy their Halcyon days, or you can flee in search of greener pastures.
Suffice it to say, the internet has always been terrible and it has always been great, because it's full of people.