To think sister is been ridiculous

[Upthecreek4]

So I had a discussion with my sister about buying of Christmas presents for the youngsters in our family mainly the children of our nephews and nieces. Our nephews and nieces are grown up with children. And these nephews and nieces are the children of our other sister if I'm. Making sense.
My sister who I think is been ridiculous has one son who is now coming up to 24 his nephews and nieces the people in question are his cousins and are a fair bit older than him and they have always bought him for his Christmas and birthday his birthday falls on Christmas day one is his god parent. My sister was very upset last year as he didn't get a single thing from his cousins last year not even a happy birthday greeting nothing at all whereas before his birthday and Christmas was always acknowledged.
My sister is saying she won't be buying our nephews and nieces children anything this year as they cut it off so brutally last year with not even a greeting card however the kids are still youngsters except 3 who are teenagers whereas her ds is now an adult but she says it hurt her how nobody even wished him happy birthday nothing.
Opinions please.

My nephew after finishing uni has only just started earning to be honest so wouldn't have had much money in previous years

He really can't expect anything, at the age of 24 if he gives nothing. I'm surprised they were still giving up to 23.

Have you pointed out that her son got 20 years of gifts from the aunts and uncles (you and your siblings) and now that he is an adult, it stops but it’s still the other younger cousins turn to get their 20ish years of gifts.

Her siblings have bought her child a Christmas gift for 20ish years. She needs to return that by buying for their children for the same length of time. Once kids reach adulthood, they can join the secret Santa.

Does she not understand that?

Sounds like nobody is particularly close and 24 is well old enough to not be upset some unclose relative didn't get them a card.

It's all ridiculous. Spend time with people you like. Obligation presents are a rampant waste.