You are absolutely right. The majority of new coins are trash, just aimed at making some quick money, without any product or long-term goals.
You can break coins down in to a number of categories:
Payments and Currency: Bitcoin, Litecoin, Nano
Platforms: Ethereum, Neo, Icon
Security and privacy: Monero, ZCash
Finance and banking: Ripple, Stellar, OmiseGO, Request
Business and industries: VeChain, Waltonchain, Exchange coins
Others: Ark (inter-blockchain), IOTA (Internet of things), etc.
I would argue there is a long-term use for less than 50 cryptocurrencies. If your product is trying to fit in to one of the categories above, tell me what it does better than one of the coins already in that category. If the answer is "nothing", then your coins is trash and unnecessary.
Example: Dentacoin. An overvalued scam coin, that is thankfully slowly falling out of the top 100.
Thanks for you catagorizing!
It's very useful for me!
Too many cryptos here for a newcomer. Now I can see tops and where they can be used
So I can research them thoroughly.