in other words you will need to still use coinmarketcap.com to get the list of all altcoins out there because this site is incomplete.
what you are missing is that these sites are like databases where they should list all the information about cryptocurrencies in existence so that people can search among them and find what they are looking for. you don't navigate a database! you search it.

not to mention that the biggest profit is usually coming from the coins outside of the top100-top500 coins.