Generally speaking, trackers are usually chained in such a fashion that a single tracker may bring in lots of their buddies. So, if you block the 1st tracker in the chain, it won’t bring in anymore. But if you unblock the 1st tracker, it opens the door for all of the subsequent trackers that do business with the 1st tracker.
Please Note: You can control whether or not to allow trackers created by site owners by going to
Settings > Trackers & Blocking.