I agree that each owner needs to look at and assess all the possible ramifications of late vs. early neuter and spay, then make the decision that is best for their dog AND the family.
I think, at this point, it is pretty clear that neuter or spay after sexual maturity has long term health benefits ON AVERAGE. What happens with any individual dog is, well, individual. In terms of "making babies" that is in the hands of the owner to prevent, and it's really not that hard to prevent with our little dogs. If it WILL be a problem, then early neuter is a must.
There are some down-sides to keeping the dog intact longer. For those with females, we have to go through one or more heats... not fun for anyone. With Pixel, we also had to deal with a false pregnancy.
For boys, it's more every day stuff. Intact males are more likely to be hit by wanderlust, so on-leash supervision or a STRONG fence are required. And while any dog, male, female, neutered or spayed, can mark, it is MORE likely than unneutered males will try it. This will need to be trained, just like potty training. And many people don't understand that it is NOT the same as elimination urination... Dogs can understand COMPLETELY that they go outside to potty, but NOT understand (until taught) that it is ALSO not OK to mark inside the house. That said, few male dogs in Europe are neutered, and they ALL learn not to mark in the house. So they CAN learn.
Finally, there are just life dynamics. Some people must use daycare, and many daycares will not take a puppy older than 6 months that is not spayed or neutered. So, if your care plan includes such an establishment, you may need to decide whether it is better for you and the dog to continue to use that facility and neuter, or to find another place. (or have in home day care, with a walker coming in once or more per day)