There are plenty of substantial discussions that go on on this forum, but they do tend to require a lot of energy and often people simply don't have the stamina.
This is also a place where people like to relax, and there typically aren't really any expectations on people for how they 'ought' to contribute. I think, generally, this is how we like it.
If you attempt to police people as you are, you'll find that they're just going to dig their heels in and tease you for it. Ironically, if you'd have let it be, people would be making more 'serious' contributions by now.
Personally, I might dip my toes into a thread and engage with the banter while something more considered begins to brew in my subconscious.
This forum is full of Ni doms, and Ni thoughts take time to form - it's a very 'slow' kind of cognition, as the connections are made and singular theses developed. However, when those thoughts are developed, they're often very profound and incisive.
Just be patient with the folks here, and you'll have your curiosity sated by engaging discussion. Otherwise, fuck off.