The problem is to find instruments that offer the same extreme granularity as the forex, its huge liquidity, and so on.
The few times I've been watching CFDs, for example at JFD Brokers, who offer a lot of them in MT4, I was very disappointed. Horrible liquidity, very poor price flow, etc.
For an environment like the Darwinex Exchange, forex offers so many advantages, and other instruments so many problems to solve, that it is not gained to have hundreds of instrumens available on the Darwin Exchange in my opinion.
Unless I am mistaken, the CFDs available at Darwinex come exclusively from LMax, and therefore from an exchange, which makes it possible to respect Darwinex's 'pure agency' DMA model.
CFDs from sources other than LMax are virtually by definition products of market maker, more or less respectable.
I have information that this CFD business is so profitable for the suppliers of these products, that they can offer them 'free' to brokers, so without payment of commissions. This is very revealing about the 'casino' aspect of the CFD world.
And even those who see the Futures as the Grail, next to the major pairs of forex in OTC, even Futures hold no comparison.