It's like a tree trunk that grows so many branches that you may become entangled in without realizing- there are mitzvot that have a basis but grow only a few branches, but these have many branches that enter everyday life in great detail so this may create a bigger obstacle for a person, and the second reason: "because of the strong lustful inclination of a person's heart in relation to them." meaning- since a person may have a desire for theft and promiscuity, this is another reason that may cause him to stumble very much in relation to these sins. 