Not to out Foaming (but I am), me and him speculated years ago that if they ever did a free trade server, a GDKP/plat guild would be the way to go for various reasons. It made a lot of sense on paper. I wasn't involved in FxIV (have been casual on the server, just hit 60 the day before Kunark), but I have like 10ish people from my Bertoxx guild involved in it and a bunch of former guildies who were raiding with them.
My perception is there's a couple key areas where the GDKP guild model breaks down for a lot of people.
1. Split payouts by themselves aren't really enough at present to turn around and kit out your character. In theory if you've made every raid, you could have bought like 1 CoF. In Classic/Kunark you don't even need gear anyway, but that isn't what makes most people play EQ. People psychologically like to get items regularly, the sort of people who aren't well set up to buy gear from raids in a GDKP guild, probably are not going to be inspired to stick around when splits is all they'll get.
2. A GDKP guild tends to become little more than a mercenary group. Minimal to zero guild loyalty or etc, everything being pure krono based. Ex. in a traditional guild people would call out if Skyfire pearls dropped to see if any CLR wanted to come loot them, it's hard to imagine in FxIV people doing that instead of selling them.
I have heard a lot of complaints from former guildies of mine about FxIV, often times these were people who loved attending the Krim plat raids on Selo. I have kind of told them that most of their complaints sound like features, not bugs, of a GDKP guild. The thing about a "side" GDKP raid, like we had on Selo and Agnarr, is that you have those main DKP raids to take care of all the people who either aren't krono lords or whales, and the GDKP raids turn into just a fun way to get a krono or so a week in raid splits courtesy of 5-10 whales who go to them and like to drop major krono on items. I think when that's all every raid you do is, it just doesn't work for some people.
That being said FxIV beat VP and largely seems to be doing fine. If there was one of the "traditional" big power TLP guilds who had come to the server with a standard guild, I think FxIV would be a #2 guild likely consigned to DZs, but I also think they'd be fine with that. My understanding is originally the guild was intended to have no batphone, and largely just acquired one when they realized literally no one else on the server was even going to batphone anything. I think the GDKP will work for a lot of people, but does have some aspects that I know when Foaming and I were speculating on it years ago, I didn't foresee.
The one big thing is if you don't do a GDKP guild, how do you really regulate what a whole raid force does with tradeable gear? That's one thing that kinda lead me and Foaming to assuming a plat guild would be the way to go--the baseline assumption is on a free trade server most people will be naked all the time selling all their gear, and trying to restrict that from an officer perspective will be a nightmare. Then again, there are raid guilds on FV that have cleared all content up through CoV, so it must be possible on some level.