Closing boarding very early
I've noticed sometimes with Ryanair, that assuming the inbound arrives early (and thus the bulk of passengers for the outbound are boarded early as well), that the doors of the plane are often closed up to 20 minutes before scheduled departure. Pushback from the gate doesn't however occur until the scheduled time of departure.
I can understand that if a plane lands particularly early at the destination airport simply because it took off early (and not because of tailwinds), then there may be penalty payments involved for making ATC rearrange a landing slot at short notice. I understand also, that no pilot wishes to spend time circling in the air burning fuel just to avoid paying penalties to ATC. Thus, the likelihood of departing significantly earlier than planned is unlikely.
What does puzzle me, is as to why a dispatcher / handling agent would close boarding (and withdraw the steps / buses) so early that it's completed far in advance of the anticipated schedule, even if the 2 pilots can't benefit from the time saving. The only things I can think of are
1) Dispatcher fancies going home early / spend more time chatting with colleagues in the office
2) Handling agent staff are on significant commission on the passengers who arrive at the gate only 20 mins before departure and end up paying a hefty fee to get rebooked on the next flight.
Can anyone more knowledgable than me provide the rationale behind this ?