When I designed my system (early '70s) the cost of a Taco 007 circulator was only slightly more than the cost of a zone valve. The service plumbers I talked to suggested the operation reliability of the water lubricated circulators like the 007 was more trouble free than reliable than the zone valves of the day. Having multiple circulators and no single point of total heat failure swayed me to go the zoned circulator route. I've not regretted my choice. I don't know today's relative costs.
Clearly zoned circulators are an easy, almost always works choice. With a single circulator more design thought is needed to assure getting the heat to all zones depending on what zone(s) are calling for heat. Often balancing valves are used to tweak the effective flow rates.
There is no one correct approach. I still envy the simplicity and reliability of the gravity flow cast iron radiator system I grew up with. A Burnham hand feed boiler burning Reading Anthracite. Thermostat control operated a low RPM motor that opened/closed firebox and flue pipe dampers in unison. During my high school days (late 50's) delivered coal was $9 a ton. For 50 cents a ton extra they would fill sacks and hand carry each sack to your coal bin. This eliminated the noise and dust. I lived in Alpha, NJ the coal dealer was in Easton, PA who had to cross the Delaware River to make a delivery. There were two bridges, a toll bridge and free bridge. The toll was 10 cents. The free bridge had a weight limit, so they brought two partially loaded trucks to save 10 cents. Ah, those were the days.