Though I think it is still an exchange that is necessary. There are plenty of dead and scam coins, yes. But there are still those coins that are not scams and dead ones. There are those coins that are well traded but has not yet come into the exchanges like bittrex or poloniex. I would say it depends on what coins you are trading.
Aside from Yobit offering whatever coins to trade with, this exchange has one major benefit, which at the same time may turn out to be a major negative aspect potentially -- it doesn't require verification. It's great for people looking to enjoy some level of privacy in this case, but the negative aspect is that the government could at any time shut it down due to it not being registered/licensed -- we all know how things ended with btc-e. I wouldn't want to risk my precious coins, and I don't see any reason for others to expose themselves to this risk in the same way.
if the "it doesn't require verification" the only reason for someone to choose Yobit they I should tell them that there are a lot of other options out there that do not ask for verifications and are not half shady as Yobit is!
cryptopia is an example with same large number of coins. but only USDT market instead of the fiats.
c-cex is another which also has the same fiat options as Yobit and despite the server issues they usually have I prefer it over Yobit.
even sites like bittrex doesn't require verification for small amounts of withdrawal daily.
there are more that I don't remember right now or probably don't even use, but you can easily find them all yourself.