Unless it's summer hols or the weekend, then I agree with you.
I wouldn't complain, or have a go at anyone, if people were being a bit ostentatious in their garden next door to me at nearly 9pm, but I wouldn't be over the moon with it either. Most people are winding down and getting ready for supper at that time. Especially if they have work the next day. Some people are (SHOCKER!) even going to bed shortly after that time if they have a very early start, and many children are in bed by then on a school night.
Hijinks and squeals in next door's garden at that time, (which is past the bedtime of many young children) is not what most people want to hear. It never happens in my quiet area that I live in now as it's full of over 50s, and middle aged couples, with only 3 families with children out of 23 house and bungalows.
Where I used to live, had 50-odd 3-bed houses in one crescent, and there were multiple dozens of kids, and some of them often played out til 10pm, even on a school night, even 10.30pm! Me and DH had to be up for work at 7am, and sometimes went to be at 10pm, and we were not impressed!
Kids yelling, music playing, dogs barking, adults jeering and cheering and pissing about after dark (at least 3 or 4 times a week some weeks,) was/is taking the piss, and very inconsiderate of others.
So YANBU @Babblepook