Why V and W destroyers could absorb escort conversions

Why were V and W destroyers easier to convert than the earlier R and S classes?

Their full naval-standard construction, internal space, and subdivision allowed machinery spaces to be reassigned to accommodation or fuel.

Full naval-standard plating gave the V and W hulls useful structural capacity for later conversion. Their internal space and subdivision also gave designers room to change the ship's duties. A common alteration removed a boiler room. The vacated space could then provide additional accommodation or fuel.