As Dervish said, this is a massive overgeneralisation, but I do agree to an extent. Advanced standards may only be a minimum of 2 paragraphs, but there's absolutely no ceiling to this, and posts can be as large as possible. The same can be done in casual, but this is far more frequent in Advanced where some players just seek to overindulge in meaningless detail simply for the sake of length and thinking that this is better, when it's not. Of course that's not all of Advanced however, but still in my experience a fair bit. And yes, it can be a chore to wade through. One thing I experienced that annoyed me to no end was when players regurgitated scenes from their character's perspective, essentially repeating the same thing as everyone else that really added little, with maybe a sentence or two of 'new' content to react to on top of that. Reading the same thing 7(or whatever)+ times in lengthy posts is boring as hell. 

Personally, I run an rp in the Casual section that has daily posting of around a paragraph to 3-4 per person depending on the scene. It helps with character interaction and rp pacing so, [b]so[/b] much better and generally makes it more manageable to read and catch up compared to long streams of text. The use of character banners etc helps to break up the text too and make it easier to read and digest. Now, I'm not sure whether or not it's 'purer', but what it does mean is we excise a lot of the meaningless drivel and waffle, get on with the story and character interaction, and make it easier to read/keep up.

And on a brief side note of collabs: I hate them. Collabs do, in my experience, kill more rps then it helps benefits. It ends up slowing activity down to a crawl when the rest of the group have to wait on two or so players back to back pming/posting (unless they endeavour to get it all done together, but rpers write at a different rate and speed to each other, so this can still take forever) and I also dislike how it 'bars' other players from really interacting or joining in on a scene that people are collabing on. And again, even though it's essentially two posts in one it doesn't help the fact that these collab posts tend to be monstrous in size too, which is a turn off for me. They can be done, sure, but I prefer a far more regulated posting rate in the IC where activity can be better maintained.