By keeping blocks small, making transactions cost more, making people do less transactions on the actual blockchain; the less transactions that occur on the blockchain, the less difficult it is to keep track of who is doing the transaction... sheer quantity goes down. If you only have one receiving Bitcoin address, and you get that at Coinbase, that address is tracked. Anything you do on the LN from that point on can also be tracked, as LN keeps track of your original payment address.
RE: Bitcoin Lightning Network LAUNCHED. Programmer explains.