I kind of half-heartedly agree with most of this, but the human era one is kind of stupid. I don’t really care about jesus’s birth or death or whatever, I just have no reason to add an extra 1 to the date for the next 10,000 years until I switch it to a 2. Mostly because I’ll be dead, but also because such a point would be so far in the future that I don’t know that any of this argument will be relevant at all.
Edit: also, you forgot the biggest one, which kind of goes along with months but not really: seasons. Lots of places don’t have four distinct seasons, they just have a wet season and a dry season, or a dry kind of summer and then a wet winter and then a dry winter, or whatever, which influences local ecology a lot. Moulding these around to roughly fit whatever any individual location’s season is, is kind of stupid. It’s better just to say what the actual season is, it’s less confusing, Everyone knows what everyone else means, it’s more specific. People have been tricked into thinking that the four seasons are a universal thing, they’re not, that’s false.