Offers are given before state school offers day, because this simply makes people more likely to take the place.
Schools know that if people have a couple of weeks to be pleased about getting an offer (lots of sucking up in the offer letters about how well DC has done to get a place against the competition) then they feel more positive about it. If they attend one of the offer holders days, some will become even more positive or swayed in dithering between state and independent because the day will showcase the shiny facilities and be a big marketing exercise. Of course some people will still be keentnobhave the free option, but for those who are really undecided, having the offer earlier gives the independent school a better chance of selling itself and tipping them in that direction. Notice independents never offer after state schools.
Some people like to think they are being kind and giving people lots of time to choose - well they are recognising a right to choose by having the deadline set after national offers day (if they do set it then - lots actually set it in offers day or before) and they are accepting that some will go for the state option, but their choice not to offer at the same time, does mean people know have longer to think about the positives of the independent. Essentially, the main reason is to benefit the schools.
And yes, lots of schools go to WL before the deadline. If they see they aren't likely to fill from first round of allocations they will start to do this because they fear the loss of good candidates to other schools. The schools who do this often have some flexibility over numbers - if some WL people take places and then there is a sudden bigger surge than expected of first round offer people accepting right at the deadline, they can run a bulge class. Some schools like City would find this very difficult - people don't seem to beer stand the space restrictions and being at absolute capacity issues - it is very different to being on a green site with lots of acres, or a town based school which has more space - many of Citys competitors simply do have more space and so more capacity to deal with suddenly having extra numbers. No-one would look to building classrooms in an underground carpark otherwise...but even this will take several years to be on line.
Perhaps it would help people to think about the motives for the actions of schools in their admissions processes to think of them more as a firm recruiting staff. What is a firm interested in if setting up - getting the best staff they can and making sure they have enough staff to fill every role so they can operate. And of course, they don't wantbtonfind they have hired more than they need. Will some people who apply be disappointed? Yes, some won't get an interview and others will get an interview and be rejected. Some might even apply and be told they have been successful but once it comes to paperwork, the business says regretfully they aren't actually recruiting now. Sometimes they even use exploding offers. I know it's not the same thing and I know that we are talking about children here with school offers - all I'm saying is that this idea that the schools are in it to be as lovely as possible to the hundreds who apply, simply isn't their main or sole purpose - they are looking to the future of the school, and sometimes that means some decisions which won't make everyone happy to achieve that. I'm not condoning unkindness or the poor communication that City has shown, nor not making policies clear and transparent, but I think I'm just saying that many people seem to struggle to see any of the process from a school point of view and only from the viewpoint of their individual situation. The decisions which are made are simply more complex than people often realise.
Do I think they've got it wrong this year? In terms of publicity, it seems yes, although I doubt applications will be down next year. In terms of clarity of communication - yes, because they didn't make it clear enough far enough in advance how they would offer - saying the process for acceptance will be made clear in an offer letter received the day before half term doesn't give people time enough to realise they needed to be around or the urgency of the decision this year. If they had made it clearer, earlier this year it would have probably been okay. Some people might have been disappointed, but they always are when things are first come first served. Can it work again another year - probably not because people will be camping out to get the places and that's not appropriate.
Perhaps they will return to the traditional system, but I suspect not. Bwhatbi do hope is that it is all through the through carefully and communicated to people at every open day from now on and in every piece of paperwork going out, so there are no doubts.
If I was applying to any school for next year, I would be checking in writing with all of them exactly what their policy is on making offers and deadlines etc. It seems you can't be too careful.