How did you find the dungeons if you didn't have prior IC knowledge of them being there?
Dungeons are quite frequently found by actually exploring. Or IC a bunch of people meet up and a first timer goes, "yeah, I want to go too!" This is especially true of my PC as there are still very, very many places on the server she has never been. For example, there was a recent advertisement of a venture to Perfidus. And that's how she got there: by IC expressing interest and IC being at the right place at the right time.
I've never observed anyone RP these Port quest items in all the times I've been around when they've been found, even when I've been with very good RPers. Instead, they generate OOC interactions and Tells.
Joseph Fogg is not a merchant. He's not even a collector. He's an antiques dealer, the person that sources antiquities and then sells them to collectors. This is made apparent through his dialog options. He keeps a public listing of wanted artefacts in a ledger in his shop, much like the Vallaki bounty board.
I presume Fogg was chosen as the turn-in point for the high-level bounties (as he existed before they did), because an antiques dealer looking for antiques was a natural choice.
No other bounties or deliveries have multiple turn-in points, so I don't see why the high-level ones should.
The high-level bounties are no more immersion-breaking than the Vallaki bounties or any of the deliveries. They are all concessions to this being a persistent game with dozens of players, not a finely-crafted 4-player adventure.
I chose to suspend my disbelief and not ask questions like 'Why does Krofburg need all this Passionflesh Fruit, where's it all going?', 'Why doesn't the Fishing Lodge deliver its barrels of fish to Vallaki by boat? - Wouldn't that be easier?', 'Why can only these 5 creatures make leather suitable for armour?' etc etc.
Both yours and Norture's responses can be summarized as "there's a lot of immersion-breaking stuff on the server, so why bother fixing any of it?"
What you say about Fogg only reinforces my point, in fact. No one has to go check out his ledger ahead of time, or even be aware that it exists (I wasn't), or go through the dialogue options. Instead, five PCs pile on a caravan and traverse through Port purely to get the XP reward at the end. Is this IC? Then why do they sit in the Mist Camp chatting while the designated seller goes and sells all the other items to the Vistani? Because the latter doesn't reward XP that they need to be present for to receive. (I actually think it would be better for the XP to be awarded when the item is first picked up, if the only thing that's going to result is a tedious, out-of-character trip that many choose to forego even with the XP reward.)
Saying "B" is bad too may divert from the topic, but it's not a defense against the charge that "A" is bad (
https://en.wikipedia.org/wiki/Whataboutism) . At least in Barovia all the items have been lost within the Domain. In the Port situation, you have an odd shop that apparently everyone in the Core knows is the only place in all the Core where you can take "antiques" from all over the Core.