Need to allow matching opponents expansions. Otherwise whoever is unfamiliar with the different cards is guaranteed to lose. I suppose this will never happen since the existing dynamic pushes players toward buying packs.
you're right that this is a disadvantage for the unfamiliar player.
Most players prefer it this way, because it allows them to access all the cards without buying them.
In any case, it would be even more unfair to force players to play only with the base set even though they paid for all the cards.
