If it's done correctly, it can be effective to take into account not only a person's ethnicity, but age, gender, and other aspects when considering whether to question him more.
And yes, this is a "profile".
An employee of the Wisconsin Electric Company, in the nineties (I don't know if she still works there) was a black woman who had to drive to a mostly-white city about 100 miles from her home (this was a temporary project, so moving wasn't reasonable). She made that round trip every day, and EVERY SINGLE DAY, she was stopped while doing nothing wrong. EVERY SINGLE DAY WITHOUT EXCEPTION FOR MANY MONTHS, but no ticket or warning was ever issued, because they only stopped her for being black. Explain, please, what was accomplished. How did this prevent crime?Almost all the crime in that city was committed by whites, but they weren't stopped daily. How does that work, according to your argument?