Many people are squeamish enough about their own urine to not want to hold a 2" long test strip in the stream, a 6" plastic device gives more clearance.

But in any case, test strips vary in how they work - some require a couple drops of urine in a specific spot on the strip, some say to dip in the urine cup until a dye mark appears. Is holding the test strip in the stream going to give the same result? I don't know.