Rationalising the reactivity of phosphoryl chloride
AFAIK it's not a particularly common choice, but Vilsmeier reagents are sometimes used to convert alcohols to chlorides (see e.g. Tetrahedron Lett. 1992, 33 (34), 4901–4904). This explains the requirement for DMF/DMAc as solvent.

A reasonable mechanism is as follows:



(see also Org. Lett. 2002, 4 (4), 553–555 for a similar mechanism)