#2 Advancement in technology
This point might raise the eyebrows of many readers, but a deeper look at this would reveal the reason for this point’s existence.
Technology is ever-improving. These days, there are multiple camera angles and very, very slow motion replays to go with them. While this has a massive advantage, the margin for error for the officials become almost non-existent as a single tiny error falls into the limelight due to technology showing its superiority.
And then the referees become the subject of severe criticism as a result of this. Hence, the officials must always be on their toes – which is a good thing – thus making their jobs much harder. But if they don’t, then they face severe criticism.