Even seemingly insignificant pieces of PII (personal information) can be used to identify you.
If you leave an anonymous comment saying that you drive a red Honda, it's not enough to identify you. However in another comment you mention that you're 45, then 3 months later you say that you work for a small retailer store. Someone can put all this together, look at when you usually post comments to determine your timezone and then make a good guess who you are. Fragmentation of information is your friend. If you've slipped too much PII, change accounts and make it difficult to build your profile.
Read more about web tracking.