The strobe on turntables is usually a neon bulb syncing to the line frequency. However, the turntable itself, if it is modern, would run off a quartz crystal. When the table was designed the line frequency strobe was a check on the operation of the crystal and motor - now the table's crystal and platter motor are a check on the operation of the power grid...

The article states a 20min/year error, but also a 14 seconds / day error. The daily error is about 0.02% - and quite irrelevant for any photographic purpose. An untrimmed bog-standard quartz microprocessor crystal can have an initial tolerance of 30ppm or 0.003% - about the same as the proposed sloppy power line timing.

I would say, though, that the 14 minutes a year is a pain in the but when it comes to resetting clocks, but then power failures mean the clocks need resetting several times a year anyway. Old analog electric clocks will be a bother, but I only have one of those left.