I'm surprised people have had problems with their dogs due to early neutering. Many rescues castrate all dogs aged 6 mths and over, and in the USA dogs are often neutered even younger than that.
My vet's advice was to get dogs neutered at 6 mths and bitches at 12 mths. My dad has his dog neutered ay 6 mths (he's 1 now) and both my mums dog and bitch were neutered at 6 mths too (both now also 1) and none have had any problems at all
I do think that if people are going to ensure their dog does not EVER have the chance to be involved in an accident, it's fine to leave then longer if you choose to.
The main problem is ignorant people who leave their dogs entire and allow them to wander.
And of course, ignorant people who let bitches in season off the lead...at the same time as entire males. In that situation, while it might be considered to be the fault of the owner of the bitch, it would still be a disaster.
This is why I have every intention of getting Ollie neutered at 6 months.