dash has an open / transparent blockchain
you have the option to mix your coins (privatesend) and do anonymous transaction (or not - as private send is optional)
obviously these anonymous transactions are not traceable
anonymous transactions are always though of as darkmarket purchases , money laundering ,...
i personal see it different and more basic
if u run a company and pay your employees in (example) bitcoin, in no time your employees will know how much coins you hold in your wallet
and what employee get what salary ! obviously that will not work (as employees will get disgruntled as of “he earns more than me” problems,...)
privacy is needed and nessacery !
other projects run a hidden blockchain (not dash), there u will have 150% privacy (not optional) but at the same time no transpartency of the blockchain (coins could possible created without anybody knowing - as blockchain is hidden + many other problems )
Data Mining (collecting information of the blockchain) is done by many companies, and most do this as a business and sell that data / information into others (propably governments )
so mixing and using Dash privatesend helps , as it “cuts the tail” to your coin history !
after mixing u start “fresh” with the coins mixed
(u know what i mean)
for better info u should look at our youtube channel and wiki , there are better , professional explanations with many technical details (sorry am on phone and do not have the info / links on me now )