Question about Reservoir computing (echo state networks)

Does anyone know why reservoir computing is only applied to time-series (data with temporal structure) and has not been applied instead of usual ANN for non-temporal problems?

According to (http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.720.616rep=rep1type=pdf) paper (page 4) it should be possible to define the leakage rate as 1 as a special case which I suppose mean no temporal learning, but I have not seen anyone actually considering it. Isn't it better to use reservoir computing instead of usual ANN to have a faster model?