They used to do it days gone by supposedly because you have a better glide range but as you generally loose more height and range by stalling the prop than you extend the range after stalling. It has been decided by those that know as dangerous and a bit stupid.
Danny Wolfe (RIP) once suggested that stopping that prop, by flying at the stall, was a potential mitigation to consider for a nasty engine fire at altitude (where there was a threat of it getting out of hand before a forced landing was possible.)
His scenario was that the fire wouldn't go out after the mixture was cut, because the engine driven fuel pump (on a PA28) was drawing residual fuel from the gascolator. Once the prop was stopped, attention could then be given to the swiftest descent possible.
Fortunately, I've never had to try it, but I often remember Danny and his pragmatic approach, with great fondness.