Math can be hard, especially when you don't factor in different time zones and account for them when booking connecting flights. This traveler apparently forgot about them and wrote a review that said, "Our flight left Heathrow at 07:55, and they told us the flight was 2 hours. But when we landed it was 10:55, making us miss our connection. The pilot didn't even tell us we were delayed".
That's probably because there wasn't actually a delay and instead, this traveler didn't take into account they'd be an hour ahead when they landed. You can fault airlines for a lot, but this issue isn't on them.