I also noticed that this statement was a bit weird. Accurate mechanical clocks were already pretty well invented at that point. By the mid-19th century the best regulators were good to about 0.5s/month, and any further development in anything but the most specialized mechanical clocks after that point were to make them cheaper, not more accurate.

As for electrical clocks, indeed rather than replacing central synchronization, the incorporation of electricity spurred the wide adoption of master/slave systems which didn't really subside until the last quarter of the 20th century. And most often the master clocks in those systems were highly accurate mechanical weight driven pendulum clocks, with the slaves being electrically driven. (apologies for the deprecated master/slave terminology, that's how they were referred to at the time)

The source article linked from the submission mentions electrically synced clocks with the master in the Observatoire.

I don't know why pneumatically synced clocks were preferred. Maybe it was cheaper to integrate the clocks themselves into the system? Patents?

<http://www.douglas-self.com/MUSEUM/COMMS/airclock/airclock.h...>

> At the Paris Observatoire a high-standard astronomical regulator clock was kept running on correct mean time by astronomical transit observations, being corrected daily. Pulses of electricity were sent every second to secondary clocks around the city, the wires being run through ducts in the sewers. Two loops starting and ending at the Observatoire carried thirteen clocks between them, the farthest being at a distance of seven and a half kilometres, or nearly four and a half miles from the observatory. The clocks were of a high standard, so they could keep good time even if the synchronising pulses failed. (The pulses synchronised the clocks but did not drive them, they were weight-driven in the conventional way) The secondary clocks were furnished with second-hands, and were placed so that they could be easily seen from the street, usually in prominent positions. They further distributed time by sending electric signals once an hour to synchronise various public clocks. The system came into operation in 1878.

Yep, in many many cases it's more important to have all the clocks be the same than it is for them to all be correct - it's just with the rise of radio clock signals and NTP it's easiest to make them all be the same by making them all correct.