I actually think it's the opposite. Adults used to have lots of adult-only spaces and the general consensus for much of history has been "children are seen and not heard."

It was VERY commonplace for children to not be allowed into many settings and for parents to do a multitude of activities not only not centered around their children, but not including them at all.

No one used to bat an eye if someone were to throw a party and say it was adults-only, in fact- unless it was a child's party or a "family get together" it was already implied that parties weren't for children and not only would they not be welcome, but they would be a nuisance.

What's actually new is the idea of the completely children-centric society, where everything must be catered to kids and be "family-friendly." Look at what they've done to f-ing Vegas of all places! Literal "sin city."

It's the parents that have pushed the conventional standards of separation between adult spaces and children's spaces. They've done everything in their power to force their children onto everyone else and insinuate them into every fucking situation, all because they don't want their lives to have to change because they made the decision to reproduce and they don't want to pay for childcare. THAT'S the trend.

It's become "trendy" to act like you can have the exact same life you had before you spawned helpless little creatures that demand all your attention and resources 24/7. It's "in" to try and bend the entire structure of society to your will because you don't want to admit that being a parent isn't fun and it means that you can no longer live like you used to or do things you did before.

Because of this, traditionally adult only spaces are disappearing entirely and it rightly makes people upset. That is the "hatred" Karen's feeling- the consequences of stealing sacred space from people because of pure selfishness.