In order for this to happen, Rocks or Clay would need its rarity changed. Both of them are extremely common crafting materials and tend to be eaten up quickly if you craft often.

Graphite is a powerful resource and should be more rare because of that.

I don't think graphite needs to be changed into a common drop, but given that my 4 miner cats struggle to keep my single scribe cat supplied it would be nice for it to be a little more common than it is. Either as a gathering drop, or, someday, as something it might be possible to get via adventuring.

Similarly, with 6 gardener cats I couldn't keep up with enough oil for 2 artists. I've been supplementing with oil from Whiskers and have bumped the number of gardeners at least temporarily up to 9 (if I need bean space some might have to go travel) to see if they can keep up that way.

building off of what nae said, clay and rocks in the grand scheme of things have more uses, there's a lot you can craft with them, meanwhile graphite is only really used for ink which isn't as much of a necessity. and think of new players, they have a higher need for rocks and clay to unlock workshops, graphite would be useless if they can't unlock scribe