Shaft drive bicycles have been around for 100 years or more. During that period there have always been a few on the market.
Although they offer some advantages in simplicity and cleanliness, there is one decided disadvantage.
A chain drive is the most efficient power transfer known. A shaft drive requires the power to be turned through a right angle twice, with a resulting loss of efficiency.
The competitive nature of cycling revealed that these bikes could not be made to go as fast as chain drive bikes, so their market is limited to those who don't mind a slower bike in exchange for keeping grease off their hands.