There certainly is. Perhaps there also isn't enough demand from crypto-gambling enthusiasts and regulars since most are focused on casino-based games such as dice, slots, poker, roulettes, and what have you. It's nice to see actual fantasy sports bookies on the crypto scene, given its recent rise in popularity. But again, no sportsbook would include this if there isn't enough demand to make it a viable addition to their platform. It'll take resources and funds for advertisements on its initial launch, too, so it's really hard to make it work currently, but hopefully soon we get it.
This seems like the most simple answer of all, there is not a lot of demand for fantasy games so casinos do not see too much of a need to offer this service to their customers, lets take a look at other games like poker, we have casinos that offer poker but it is nowhere near the offers we get from other games, this means that the demand is not there so I can only imagine the demand for fantasy sports is even lower so it is not surprising we are not seeing anything like what the OP wants.
However once we get more adoption I really think people are going to migrate from the fiat platforms to crypto platforms as it is happening already with many people preferring to gamble with cryptocurrencies than to gamble with fiat.