Thats somewhat true, but that's also what the Tag system is for.

the RP we've used as example (our SW RP) is tagged both Casual and Advanced, as its appropriate for both.

With the current guild architecture, a thread can only be placed in one section, but it can "belong" to several.

If someone's turned off by a thread tagged with "casual" having posts that exceed the 1-2 paragraph "limit", then they are turned off. There's nothing to do about that. That happens due to all sorts of other parameters too.
Wrong genre, wrong image on the IntCk, sub-optimal layout. Too little information. Too much information. etc.