The article is claiming that clocks that only show time truncated to a minute are off by an average of 30 seconds, which just isn't true in practice. When I say or hear 11:30, I assume it can be within 11:30:00 and 11:30:59. Humans rarely need accuracy to the second beyond this, so clocks intended to be used by humans truncate to the minute without causing problems. To say they are "late" is a real leap.

I mean, you can reduce this to absurdity too. A clock truncating to seconds is off by an average of 500 milliseconds! The problem is no one cares in day to day usage which is what human readable clocks are made for.