This is good advice. We should not hold any coins that don't have a regular dev team support. It is just too easy to create a clone coin now.
Then you can instantly discard 95% of the altcoin market. Most projects hire devs in order to improve implementations or to add extra features other coins have been rocking for years, all to please their noob backing.
Yobit for example has coins listed that haven't generated even $100 in 24H volume once in the last 12-24 months. In the same way, Binance is dealing with a large number of shitcoins as well.
People make fun of exchanges as Coinbase for not having many coins listed, but they forget that this is how an exchange should be operated. The majority of the altcoins are nothing more than pest that should be eradicated immediately.
Not a surprising thing for some exchangers like Yoshit which do keeps on accepting or listing shitcoins not just to mention decentralized exchangers which also being flooded by erc20-token shitcoins too. For popular or top exchangers it is just right to delist these coins which doesnt really have volume at all to free up some space and would open doors to new ones and the cycle continues.