ranking of cryptocurrencies becomes outdated in my oppinion, its quite easy to create a currency which has a higher marketcap than bitcoin, but a corrupt sect arround the indexes prevents listening of those.
with the end of national banking cartels a time called "coins of style" will come, in this it will be more about a cryptocurrency and about its management and much less about a pretended selffullfilling ranking.
this could then also help prevent to get the market divided into new marketmovements. that want to free themselves from attention monopolies of established top 10 coins.
etc.
regards
You are totally right! It should not be based on market cap instead it should be based upon the popularity of the cryptocurrency. Just like what you said, it can be tampered and easy to create a currency with huge market cap. However, it will become useless if the people does not want that coin, so it is better to look upon the usage of the coin, price, volume and dominance so that they will sort well.