I know what you mean OP. Similar scenario when I take my grandchildren out (girls and boys aged 6 and under).
We're near (less than 5 min walk) a huge playing field (about 3 football pitches in size) with goal posts, a marked pitch and an area with swings, slides, zip wire, other play equipment which is accessed through gates as it is surrounded by waist high railings. Equipment at one end is obviously for older children and the other end is obviously for younger children - baby swings, short slides, small roundabout, marked out path to resemble roads and roundabouts etc. The railed off play area is surrounded by a ring of dog dirt - but that's another thread.
It's generally older boys with footballs who ruin the atmosphere when I take my grandchildren there - yes inside the equipped play area, yes kicking hard football's aggressively where the little ones play. What is it with sending footballs a mile high without any control of where they land?
It's hilarious.
It clearly states at the younger side of the play area that the equipment is for children 0-4 yrs. My 6 yr old granddaughter goes off to play on the older section of the play area or sometimes sits with the younger ones on the roundabout or supervises them on the slides. Sometimes the equipment is inaccessible as teenagers are sat on it - smoking, vaping, swearing and spitting - not using the equipment (not meant for their age range), just sitting on it.
Personally, I don't think children's play equipment is a suitable place for anyone to be slamming footballs about or for creating thick clouds of pollution for the little ones to walk through.
When this is pointed out politely to those concerned it's met with abuse. 'F* off fat cow.' is common. This from very unobservant louts - for a start I'm not fat? Or a cow?
This is in fact not a bad area - house prices are high here and the secondary schools closest are single sex. But it's definitely a bad attitude area.
There are goal posts to play around just a footstep away.
Don't try and justify that behaviour - it's just unacceptable.