Bear in mind, this is an RP event. Telling people they need to limit their posting times/intricacy would defeat the purpose of calling it an RP event, I would think. I would catch holy hell if I tried to tell anyone else how to RP, so why would the hosts of the event implement rules to tell other players to do the same?
Furthermore, not everyone has a keyboard with which to type out their posts, namely people who are playing on the PS4. Some people still don't even know they can hook one up to their PS4 at all! A few friends of mine didn't know until I let them know, and even I wasn't for sure. I wanted to still think you could only hook up a PlayStation brand keyboard (which turns out is not really the case). So, of course it takes those people a longer time to post, even smaller posts (nevermind longer ones). Hell, some people are just lousy typists. I try to have as much patience as possible because you never know the reason, unless you ask them.
Lastly, if you believe for any reason you can't stay for the entire event, then you reserve the right to not participate. I set aside enough time that I can stay for this entire event if I need to, even if it goes to 3am for me, and I'm on PST. If I don't think I can stay for the whole thing, then I just don't participate. I'm not always able to attend at all because of work because sometimes I gotta close, but I accept that. Bottom line is, the hosts of this event are doing the best (I think) they can, even going so far as to add another bracket to accommodate the larger turnouts. I'd also like to add this also isn't the only (although perhaps the biggest) event there is out there that uses the same style of RP fighting. There are plenty of smaller events that occur throughout the week at aren't as hectic on the chatbox as this one. If the Grindstone is too overwhelming, then I would encourage you to try one of those.