If you look at Coingen.io , it will soon be completely impossible to actually list all new coins. Also, back when Cryptsy was really the only altcoin exchange, things were different. Now there are multiple altcoin exchanges with lower requirements for listing than Cryptsy -- CoinedUp has added a huge number of new coins recently and now there's also NEWCHG.com who has entered the altcoin arena, so there will be competition amongst the three to list things.

It's rather unfortunate, really. Once upon a time you had to have a pretty decent coin to get listed on an exchange. Now, you almost have to get listed since if one of your competitors lists you and you don't follow suit, you're going to miss out on business. So if CoinMarketCap.com lists everything that is on an exchange, I presume CoinMarketCap.com will be adding a lot of new coins in the near future.