So people aren’t allowed to moan about anything because others have it worse?
Not at all it seems you misread, or didn't bother reading at all, the last few posts. People can complain about whatever they want. If you read further up a poster said:
On behalf of the many thousands of women who would desperately love to be a Mum , I suggest you get a fucking grip.
And further down someone said:
Quite frankly, all the women with infertility problems dismissing your disappointment could also be told to stop whinging and appreciate that they’re living in a developed country and have plenty to eat
Point was people are free to complain, moan, be disappointed, etc whenever they want and others can suck it up because if we want to nit pick up then there is always someone worse off but it doesn't help to dismiss others concerns.
Helps to read and comprehend the message trail for context before jumping to conclusions :)