One of the big things they stressed, at least for the dogs, was how important it was to play with the them. Expose them to people, scratch their ears through the grate on their kennel, pay attention to them, etc. etc.
The reasoning being that dogs who are used to humans, and are affectionate towards them, are more likely to get adopted.
If this was for dogs, it would be a HUGE benefit to them. Getting them out around people is almost always a good thing for them.
Just to give some perspective, my own cat loves people, strange or familiar, it doesn't matter at all. Take her to the vet in a car though, and she will go mental, crap and pee in the cat carrier, meow and hiss when she gets let outside of it (never does that otherwise) and be extremely edgy for sometimes 2 days afterwards. I wouldn't go as far as saying this is 'cruel' to the kittens, and it's great that the proceedings are donated to an animal shelter, but I'm pretty sure the kittens will not enjoy it nearly as much as the people who get to cuddle with them.
Though, normally it's free, and the animals aren't delivered by a taxi service.
From the article "You will have a chance to adopt the Kittens! YES, IT’S TRUE! For more information, please chat with the shelter representative that will be assisting with kitten wrangling!"
All kittens come with a shelter representative who will presumably keep an eye on you and the kitten.
Sounds harmless to me as long as the animals have long-term support too.
I will adopt any cat that forms an attachment to me in 15 minutes of petting (I don't own any cats).
It never ceased to amaze me how quickly they would get adopted after an off-site day; seemed to just hit a reset button on their stress levels.
You have to select cats that are well-socialized, but it can be very healthy for both participants if done properly.