- Schools have varied definitions of when to place a child in kindergarten. In CA, the rule is "5 before October", in other places it may be sooner or later. If all humans are born at around the same time/in the same month, this confusion would cease to exist, as they can simply ask for "turning 5 this year".
- Birthday season. Birthdays will be more exciting, almost like the Holiday season. We also will only have to hear birthday commercials during only part of the year, as opposed to year round.
- It's better. If the baby develops in the summer, it will receive fresh nurients from fresh in-season crops. If the baby develops in the winter, it will have to receive imprted pesticide synthetic foods.
Enforcing a mating season would attack freedom of choice. We evolved this way for a reason, the best thing for our species was to not have a mating season, and changing that, just because we think we should, would be harmful for us.
Also, on the funny side, would you want to share your birthday with most people you know and have trouble organizing a party because ten of your friends want one in the same day too?
Even if we disregard the fact that human biology is structured so that we do NOT have a distinct mating season (and that this was an evolutionary advantage over animals that did), how ridiculously dictatorial would it be to restrict when people could have sex or conceive? Never mind all the people that take a great deal of time to be able to achieve one pregnancy that "sticks".
We do not live in the third world, where there is any issues of nutrient deficiencies. Not to mention that infants require a great deal of nutrients their entire first year.
This is really a nonsensical claim.
Resources for pregnant people, babies, and children will be stretched thin among too many people because of all the children being born at the same time and the amount of pregnant people who will need care, maternity leave etc. at the same time.
Schools will be overcrowded, they are already, but even more so. Things like diapers, baby food, formula, clothes, will all be sold out and in much higher demand if babies are born all at the same time, leading to competitiveness and high stress. Day care centres will be run ragged by the overabundance if infants they will have to care for, leading to lower quality care.
Let's face it, the lack of diversity in birth dates and star signs would be pretty boring too.
Also, parents should have a baby when they wish to and not just go by some mating season rule, we're not animals.