By having a design which does not allow for Balancefishing. The reason we fished for Balance was because AST back then was capable of giving people what we now know as Brotherhood, the 5% damage buff, for 15sec, potentially each minute. Compare that to other options, such as 'no damage (because you got Bole)', 'no damage (because you got Spire)', 'no damage (because you got Ewer)', and two flavours of 'a bit of damage but not as much as Balance'. Of course people were going to fish. But if the cards ALL give damage in some way, such that the 'extra effect' is the focus, eg the Mit on Bole, the MP on Ewer, etc. then Balancefishing isn't needed. In fact, the Seals (and Astrodyne) are the answer to Balancefishing from SHB onwards, even if the Balance was 'the best card', the reward for doing the 3 seals just needs to exceed the Balance's contribution to make 'play slightly worse effects for a massive payoff later' work out to be 'the best option'. As I've said previously, the easiest way the devs would have access to, to lower the 'damage variance' of the cards, would be to keep them singletarget and keep Divination as the 'big raidwide partybuff'. Then the cards only need to be balanced as 'Balance contributes this much RDPS, so the other cards should do this much too, but with their own way of applying that damage'. And then once that's done, slap the unique effects on them. Bole gets mit, Ewer gets MP regen, Arrow gets movespeed or something idk. And you wouldn't fish for one over another per se, because you'd still have Seals to play into I'd assume (since the devs seem to love that system).
I can guarantee, with 100% certainty, that people will not Balancefish if the design is set up to avoid that outcome. It's not some situation where 'we have RNG buffs, so we cannot have any outcome from them except 'players try to get the best one'