I don't think Fractal hurts the game at all. ...
About new creature card ideas, I do think that it makes card balance a bit more complex. However, I don't see this as a bad thing. If a creature is inexpensive to the point where it is abusable with Fractal, it is also inexpensive enough to be used in a speed rainbow deck, which almost all consider to be the premier PvP deck.
It is not just the cost of the card that you should consider when fractaling it; it is also the effect it has (if any) when played. See Deathstalker for example. If that Scorpio had attack stat, fractaling it would make a huge bomb of poison on your opponent, which would clearly be insane. It would take time to get rid of those from the field, and then you'd get bombed by another fractal.
However, if you were allowed to play 1-6 scorpions as you draw them (drawing them being the more important part), having a scorpion adding 2 poison counter at the turn it is played would not be "overpowered" at all. It would be a good card to have and play; valuable asset to a deck.
So what happens? Scorpions are given 0 attack so you have to buff it first. This automatically negates fractal, but makes the card a LOT weaker as you are suddenly forced to have another element in your deck, with being limited to only 4 buffing elements, and you have to take those buff cards in your deck. It not only makes your deck slower and prone to bad draws, it also limits your deckbuilding a LOT. That is the prime example how Fractal is actually limiting this game. We will never be able to have powerful "fractal-able" cards in the game, and I've seen many very interesting abilities that would just be insane with fractal.
Now, is fractal overpowered? I wouldnt mind it being toned down, but definitely does not break the game at its current state. But the only reason it does not break the game is the limits it puts on other cards.
Maybe an idea written in this thread, with some cards being unfractalable (lol at the word), would give some breathing room for new cards.