Load planning is sometimes last minute. Pilots change the amount of fuel they want on board at their discretion, no shows affect zone loading, baggage is weighed before going onto the aircraft. If 2 people are moved, you can bet the aircraft is JUST outside the C of G envelope. Easy for AC to assume if everyone showed, if a few more bags were able to all fit in fwd hold the move would be unnecessary. All of this means the pilots and load planning get final W&B at the last minute.

There are still humans doing the W&B work in Toronto. Likely there are occasional waits for paperwork while processing other flights.

It really doesn't. Believe it or not there are times W&B are just outside limits, other times it is more predictable. They will move beforehand if they know there is a very good chance the loads aren't distributed.

I also know this 'crappy' system is able to proactively block sections of seats for W&B, I've seen it before presumably on flights with odd cargo arrangements or obvious Y/J imbalance. Y shows full on the seat map, meanwhile it leaves wide open (on ex-YWG too, so no irrops). So the system obviously isn't that rudimentary.

Because the only benefit for status holders are opups.