Gold pebbles right now barely matter at any point in the game. Early game you'll get a couple from digging clay, but not enough to ever make a nugget. Mid game you basically don't see them because the local pools are emptied. Late game you get enough to make nuggets via smelting and arguably you could just remove them and slightly increase the gold nugget smelt rate for the same effect.
Seems to me like there's an early game niche where pebbles are basically thrown out. Would make sense to use them as (or craft them into) an early curio that's very high in LP/HR/Weight, but a low total weight.