Among the coins that have good privacy properties are indeed Monero because it has a different source code than its other Crypto
But to develop Monero to be compatible with some applications is quite difficult because it is different from other crypto, compared with ZEC, NAV
It's not rocket science. By now a lot of exchanges and other services have done the integration.
There is a segment of the crypto community who want to be lazy as fuck and do nothing but support Bitcoin clones. Maybe that made sense in 2015 when the crypto community was poor and everyone was trying to keep their hobby crypto business alive on the cheap while working day jobs, but in 2017 these are all significant businesses that can afford to hire a low level developer to support a few new APIs.