I know I'm not the only person to think of this (in part due to this Tumblr post) but why did Dumbledore/McGonagall cancel all the exams at the end of Chamber of Secrets?
So basically if you're in your 5th or 7th year you're out of luck because you're not going to get your OWLS or NEWTs LOL. But that's okay, I mean, you'll only be stuck with no qualifications for the rest of your life. At least you'll be happy for now as you can start the rest of your life today - and by rest of your life I mean the boring tedium that WILL be your life working in a shop, living in a squalid flat because you never got your NEWTs because you couldn't sit for them, because I cancelled them LOL. Dumbledore out. Ruining lives since 1881
I can see why it fits in the ending of a children's novel. Rowling needs to get to a happy ending pronto so she's all like: Lockhart is gone forever, Hagrid's released, the petrified people are OK, Gryffindor wins the House Cup, exams are cancelled, huzzah! For the lower year students not having to do exams is a treat (though obviously not for someone as studious as Hermione!) as it circumvents hours of boring revision.
However, for the older students, exams are the means of getting a foothold in the adult world by gaining OWLs and NEWTs. Cancelling the exams seems cruel to those people, especially in the light of this quotation:
Ten minutes into the class, Professor McGonagall told them that their exams would start on the first of June, one week from today.
"Exams?"", howled Seamus Finnigan. "We're still getting exams?"
There was a loud bang behind Harry as Neville Longbottom's wand slipped, vanishing one of the legs on his desk. Professor McGonagall restored it with a wave of her own wand and turned, frowning, to Seamus. "The whole point of keeping the school open at this time is for you to receive your education," she said sternly.
"The exams will therefore take place as usual, and I trust you are all revising hard...Professor Dumbledore's instructions were to keep the school running as normally as possible," she said. "And that, I need hardly point out, means finding out how much you have learned this year."
Chamber of Secrets, Chapter 16
If holding the exams was still important when people were at risk of life and limb before the Chamber is closed then why cancel them when that threat is no longer there?
Moreover, how did a generation of Hogwarts graduates survive in the wizarding world with no formal qualifications?