Yes. The game starts wigging out at the 1 billion platinum number, due to the number of digits of platinum it has. For example, placing it in your bank will crash the client.
Drops should be: Quest items, Usable items (weapons, armor...food and drink), Cash and TS components (where this includes gems). I would go as far as quest items only drop if you have the quest (where that is possible).
I do not know the upper limit on platinum coins one can have. You have at least three storage buckets for platinum (on character, in main bank, in shared bank). I did not bother to check the guild bank. I only deal in 10s of millions at a time. I have no issue. I assume, I can go up to 99 million and change. Never had more than 30 million at most. That puts the upper limit at just under 100 million in the shared bank + just under 200 million per character on the account. So, it should be possible to gather over 1 billion platinum into one account. Good news for boxers. I am willing to test this, so please parcel me those millions in platinum you have gathering dust. Of course, nothing will be returned. My alts will put it to good use after the attempt
That is exactly how it works now, however the first 18 years of Everquest it was not this way. I guess this is just part of EQ being in maintenance mode.
Why spend developer time making items that only have a purpose of being sold to a merchant when you already have limited time for them to do things?
The classic Luclin vendor gems would have been a nice flavor touch. Indicolite, Iolite, Luclinite, Stralagite, Stratolite etc. Maybe use forms of those for a collection set?