A hell of a lot of people saying this doesn't ring true to their areas and gumtree, pets4homes, rescue pages etc have no dogs of this age group available.
One poster claimed there were thousands of 8-12 month old dogs available on pets4home in her area but didn't post a link or provide any evidence (unsurprisingly as that is patent bullshit).
I do think people need to remember that rescues are business's too and have been ramping up their adoption prices and, as is always demonstrated on these posts, setting criteria for adopters that is near impossible to meet.
I've been involved in rescue overseas where there is definite immediate need for dogs to be taken in and a flexibility between permanent, foster, bridging etc to ensure dogs survive and aren't ruined by spending time stuck in eg. a kennel and we have made sure that dogs are neutered, immunised etc without requiring £500 from a prospective adopter.
It always gets justified and glossed over on here but requiring ridiculously high standards for potential adopters eg. dog never being left alone therefore never working outside the home, no children, no other pets, large garden, high fences etc etc makes rescuing extremely difficult which feeds into breeder demand.