I understand the fact that investors should do their research before investing into any project or coin, but MarketCap sites, such as, CMC, CoinGecko and the likes, also have some roles to play.
Reputable exchanges do screen and scrutinize every coin that is listed on their sites and peradventure there is any already listed coin found suspicious of scam, it will be delisted. With this, i also expect that MarketCap sites should do the same, but these days, it seems they are left and displayed without doing the needful.
If this is done with due diligence by deleting or delisting scam coins, it will go a long way to help the system and at least make it safe to some extent.
The easiest way to clean them out is to get rid of projects with near zero every day volume. By the way, take a look this article about the real situation on the market (
https://blog.goodaudience.com/bitcoin-market-value-to-realized-value-mvrv-ratio-3ebc914dbaee) and pay attention to Current Environment section (as well as the whole article). I find it very interesting.