It has a high CNS stress than doing L2S so if you arn’t recovering it can be a problem and as a result some athletes with less ability in this area respond better to L2S. For me if you want to break the WR or run under 10s then S2L is the way to go for certain because an athlete with that ability will generally respond excellently to it.
Having said that I’ve used it with success with developing athletes (12-15) and 18 year old 13s girls down to top level College students for both sprints, hurdles and horizontal jumps.
As for why fewer people use it. That’s just because of tradition. If you were brought up on it then as a coach you will understand how to implement such a programme. If you are trying to work it out and are used to higher volume models then you will often be uncomfortable with using such low volumes and so push the total training load beyond what the athlete can handle (because you will always prescribe too much volume initially). Remember if you are used to running reps at say 11.5s and suddenly every workout you are running 11s then that is a massive difference and it will take a year or so for the athlete to adapt to the change in intensity. This is a long term project not a 1 year wonder fix.