Sometimes yes, its tricky when you work with a large shipper but a section of their business is run through a broker. For example, we run flatbeds for a direct shipper, but also do dryvan work for them which is facilitated by a broker. So when the broker has a clause of "no back solicitation" it doesn't make sense. In our case all parties are involved so its understood what's going on, but I can see it becoming a problem when everyone's not on the same page.
Also some of these clauses are ridiculous: "No solicitation of shippers/consignee's, shippers customers, consignee's customers, shippers group of companies or Consignee's group of companies will be tolerated" Um ya dont know about that one buck oh.