While Invisalign is an excellent tool for moving teeth, it is not the best choice for everyone. Certain movements are easier to obtain with traditional orthodontic brackets, so for very complex cases, this may be the better treatment.
Additionally, Invisalign outcomes very much depend on patients being compliant with treatment and wearing their trays at least 22 hours per day. Many teenage patients (and sometimes adults) aren’t willing to commit to wearing the trays all the time but still want straight teeth. They may be better off with attached brackets so there is no option of removing trays from their mouths.