Because there are no primary sources. The idea that Eye of New = mustard seed seems to appear of of nowhere in 1985. If there are any earlier sources, primary or otherwise it would be very interesting to see them.That link questions, an gives the (appropriate) critique that people don't cite primary sources, but provides no information other than that.
This is logical. But since when has the D&D economy ever made sense?Flesh to stone is a 6th level spell, and it can target one creature. So, you get at most two eyes for each 6th level spell cast. That's not many. For a spell component that has no cost, that seems like a costly, bottleneck of a source.
It’s definitely the eye of a beast in D&D. It says “eye of a newt”, and not “eye of newt”, and hex is a nasty warlock spell of death, so a nasty component makes perfect sense. Also, it’s not consumed, so it could be an heirloom that you’re carrying around. Now, the real question is how on earth the warlock can produce the eye from a spell component pouch and put in back inside in the span of a bonus action. I guess that’s magic.
Count me in the list of people who didn't know that meant mustard seed.
This is logical. But since when has the D&D economy ever made sense?
Except my Rogue just leveled up to level 4 and picked up the spell with Fey touched but she has no spell components, does not have enough money for a component pouch and is not in a civilized area. So she has to find an eye of a newt. She has a feather and a bit of fleece for her other spells that require a component.Note, that as a game spell component, it is listed without a cost - so you don't actually have to worry about it. It is flavor text, and can be assumed to be in any spell component pouch.
no components are used unless a spell states they are, so a component pouch only needs 1 of each component for every spell level 1-9 excluding those that have a cost or are consumed.All components are consumed on casting, unless the spell says otherwise and spell component pouches hold multiples of each spellcasting material and it is assumed that in down time, or during rest time while on adventure, that you are freely able to replenish the materials used during the day. That is why there is not a cost for them.
Edit: I may have mixed a little house rules into that, but even so, what is in a component pouch is not infinite, so either scrounging for refills or buying multiple pouches is necessary.