I think that is what the intent is.
It will totally slow down the rate at which people can get nymphs. I personally think they should be able to be won in spins, but maybe using a different formula than the current spinner system.
I think the current system works something like this:
1. pick a card from your opponents deck
2. if it is a pillar return to step one
3. if after 10 picks it is still a pillar keep it.
4. repeat steps 1 to 3 until Four cards are chosen
5. Spin 3 spinners using the 4 cards chosen
6. if all 3 spinners return the same card, you keep it.
(might be completely simplified or completely wrong)
But I think Nymphs should be winnable-on-defeating an opponent, just extremely rare:1
1) Not many opponents will have them to start off with
2) The chances of it coming up in the spinner at all are very slim
3) The chances of it appearing 3 times in the spinner are even slimmer.