Story

...but I simply don't understand the problem.

It's possible that programs not equipped to handle the extra second could have an issue.

What programs? If the clock is not correct I might have a minor problem with builds. I might recompile more than necessary. So What? But crashes? Especially so boring systems like websites? Possibly "lightly" corrupt databases, yes. Perhaps the order of a few posts mixed up, yes. This should be all. I'd probably have think hard how to crash a program on purpose just because the time is one second off.