They're not hard work. They're just not the same as you.
My exh had a big family and would often have big events. We rarely attended. They were just very different people to us. What they considered entertaining, we found boring; want they thought was fun and enjoyed were activities we actively avoided.
We didn't enjoy their company on that level. We didn't like the way the other children of the family behaved and didn't want ours to be exposed to it.
We had nothing in common with any of them and beyond, "How are you?" small talk at the start, we had no interest in what they wanted to talk about any more than they were interested in what we wanted to talk about. We had no common points of reference.
They thought it was enormous fun and thought we were 'stuck up' and 'hard work' too.
In short, they weren't our sort of people and we weren't theirs. Had she been aware of MN, I can quite imagine my ex mother in law posting similar!
I personally think it's fine to sit in quiet, private judgement of other peoples parenting 😉 and I know they judged ours. It's fine to have a private moan about it with your husband. It's fine to speculate on the future impact of it because we all do it.
But it still doesn't make it your business. And it still doesn't make them wrong and you right.