Aside from the business end, it is a good learning/ training gradient. Instrument and commercial knowledge/ skills do not necessarily make a good primary instructor. Training for, and experience in, primary flight instruction does that best.
With the lack of LSAs available, it's a catch-22. We need more CFI-S instructors available for school operators to invest in the LSAs, and more LSAs for aspiring instructors to start.
Too much negativity on the CFI-S for folks to get it going. Should be a required CFI starting position for a couple hundred hours before advancing to instruments and commercial operations.