With the new Sapphire Yak, yaks have to be the ones to actually gather from the faeria wells to receive any benefit from it. However, even if you have a yak in position to gather, having any other non yak unit next to the well could invalidate your buff. It makes the Sapphire Yak play-style very clunky in decks that are not completely comprised out of yaks, often causing you to position units sub-optimally to make sure the yak receives the buff. Sapphire Yak is the only card in the game to require a specific unit to gather from the well to receive the benefits (aside from Luduan), so making this change would not effect any other cards unless you were running Luduans in the same deck.
If Luduan does not have gathering priority it could probably also benefit from gaining it.