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.
this is where the weaknesses of the system that the marketcap currently has, whether they are for whatever reason do not want to delist coins that have indeed committed fraud or have great potential for fraud. Most likely this is because because the marketcap is free, does not hit the same thing well or not, the most important thing is there are certain conditions that must be fulfilled for the listing, even if cmc has to remove the coin scam, they should also delete gambling and multilevel marketing's coin.