Kestrel said
'High-casual' is redundant as a term to begin with. As a GM you're free to add rules and expectations to your games at pretty much your own wims, as long as it doesn't go below section-standards, which are all more than reasonable.
I don't really feel that the term is redundant. Isn't it sort of naive to think all roleplays perfectly fit within the Free, Casual and Advanced archetypes? Some roleplays in Casual have 'lower' standards where most CS's are Mary Sues, incorrect grammar and punctuation and some posts so short that they're almost impossible to squeeze the word quality in. I'm not judging this, people roleplay for fun and some people feel putting in too much time and effort takes the leisure out of it.
However, some don't. If I spent time creating an original, detailed character and making quality posts, I would prefer being in a roleplay with likeminded people. It wouldn't be very fun for me to roleplay with dozens of Mary Sues who barely cared about character or plot progression.
'High Casual' has been associated with length simply because when a person bothers to invest time creating quality posts and character sheets, they
tend to be longer. I agree sometimes posts are filled with fluff which make them painfully repetitive to go through but just take the average lengthy post and compare it to the average short post; its obvious which is of higher quality. People who bother to write lengthy posts also tend to be more committed and attached to a roleplay. Theres also less speed posting which is frankly quite a selfish thing to do.
Some 'High Casual' roleplays are more detailed with better use of english than some roleplays in advanced.
Some people do the "Then you just move up to Advanced." argument but the Advanced forum has a much lower population. OC spam and banter happens less and IC posts don't tend to be very frequent or consistent in posting time...