There's some mutual bad blood between banned bois and Jesse. I just try to ignore it. He seems like an okay guy. I don't often interact with him. Honestly kinda surprised he hasn't given me a warning for some locked threads over there.
Some guys over there are simply easily-roped into hatred towards CGC (and/or the boards) for some reason. They're a smaller community, yet they seem to attract much more of those types of people per group-size. That's just from my limited experience (5 years reading the forums here and 3 years reading theirs - I joined both boards long after perusing).
My summary would mostly be: CGC seems to be more logical and CBCS seems to be more emotional. The majority of both communities is great, though. The CGC boards are more-populated and easier to find what I'm looking for, though, hence my abundance of activity here.
There's probably a 'little sibling' syndrome going on, too. CGC came first and is #1 in the business. The fans here aren't really concerned with anyone else. CBCS is, far-and-above IMO, #2. They're fighting for 'attention'.
It's virtually the same as the MCU vs Worlds of DC. There are DC fans who just hate everything Marvel because WB couldn't get their s^&* together to be enough competition for consumer attention. I like both Marvel and DC. I like both CGC and CBCS communities. You'll never completely avoid the competitive toxicity, though.