First of all most of the exhcanges you shown are fake volume...
But any way for the big names:
Also just bc it a common practice doesn't every exchanges want to do it(nor does being common mean it has to be half) It common practice bc most companies recognize it is legit. Also was way more common before all these new (questionable) exchanges came. It also quite common in noncrypto markets.
Exchanges do it if they want to. Phonloeix did this most likely bc it a bank so trying to bring some elements of it back and bitmain invested it it. Futures are great profit machines but can be to much work for exchanges who can just list altcoins. However futures do give free press and is a great way for other exhcanges to study which coin might win. Basically there a bunch of reason why an exchange may or may not add futures. But it is still a common practice.
Exchanges shown to do this:
Bitfinex
ViaBTC and Coinex
Yobit
Exrates
gate.io
Hitbtc
AEX
BitAsiaEx
coindcx
Lbank
Some other as well
And any exchange that Eos and tezos, tron and other icos before they went to the own chain could be said to be to futures for they were only erc20 token with no real chain present. But that iffy.

It not the faint of heart. Like the 2x futures shown you might lose it all. However it a common practice and very risky. High reward for high risk. Treat it like gambling.