A decent filter on a network (think pi-hole and next dns and the like) helps block adverts, trackers, scam sites, shady pop ups as well as bog standard porn sites etc
Internet is full of things that it’s easy to accidentally stumble on that you wouldn’t want a young kid to see and I think it’s a reasonable step to have some basic levels of controls on your own network
The onus is on the parents to manage internet access in a way the feel best and shouldn’t be forced or assumed. definitely not to porn sites (or any other site!) to collect entirely unnecessary personal data which would inevitably get leaked.
I totally agree and I put in a good faith effort to block that stuff from my kids’ devices using a pihole and what’s available on their phones. But I remember being their age and getting away with things because I figured out the workarounds.
At the very least it’ll teach them a little about networking and computers which will serve them well in their careers.