There were many athletes in my group using S-to L or L-to-S depending on their response. S-to-L is hardly restricted to my group with E Germany using it primarily and Poland using it by response, and many individual coaches going back to the turn of the century.
Fractured metatarsals as a result of S-to-L???
Look to prolonged exposure to hard surfaces, regardless of approach.
I believe PJ Vasel wrote a history of sprint training over the last century for the British coaches’ education group. You might find something there.
As for the choice of training method, a debate was held some time ago over there with Tom Crick taking the S-to-L position. You should be able to look it up.