I think it is fair enough for husbands to step in for their children who are too small to do anything for mothers day. And it isn't a problem that it has morphed into an appreciation day for a parent rather than a church thing. Traditions change, it's no big deal, especially as there is Father's Day too.
I say this as someone who used to spend a great deal of time choosing a Mothers Day card that said very little because my mother was pretty bad. And as someone who had nothing on mothers day for years due to divorcing. No biggie.
However, son knew to give me a card and small present as he got older - again, not a big deal, but a nice gesture of appreciation, and since I help him a lot still, it's part of reciprocating that.
This is where it becomes a big deal though. When women turn themselves into drudges, who sacrifice themselves and thier well-being to partners and children who take them for granted; when they don't speak up and become martyrs; when they are pinning all their hopes on something at Mothers Day to show them they truly are appreciated in spite of appearances.
Then it doens't happen. No-one gave the children the memo that the deal was Mum would sacrifice herself and they would love and appreciate her. Partner doesn't care either. It's a nasty realisation for some people.
They haven't left, because they are in denial about how bad things are. They also tell themselves this is normal, and respondents on MN seem to give reason for that, saying it is ridiculous for a grown adult to expect presents on any day of the year, especially not a commercialised mothers day and especially not off their partner. It gives them reason to keep their bar low, and also results in ridiculous 'testing' behaviour like saying you don't want a card/present and then getting upset when you don't get one. And other passive-aggressive rubbish
As a rule of thumb, by the time things are bad enough to post on MN, you've gone beyiond the point where a present and card on mothers day would fix it. But lots of people don't realise that until the much-hoped-for card doesn't appear.
I hope this has fully explained, OP, and that you now have some understanding of those posts