The team believe that, with Synergy of Serra, they are creating something different. There are already multiple blockchain card games, where, if you are able to, you can pay to acquire powerful cards for your deck.
Synergy of Serra's main game mechanics mitigate against pay-to-win becoming dominant.
Every player has to share their cards with their opponent and build their deck during the match. This means that if one person has more powerful cards, their opponent will have an equal chance of being able to use that card.
Some may see this as a disincentive to buy cards, you can read more about why it is still good to own your own cards in 'Why own cards?'