I don't do it and i agree that some might have relationship problems and protest too much.
But i find it equally sad to assume hidden misery about others. I see it quite alot here i.e.
-'Big wedding? I bet there is no love'.
- 'Nice holiday? I bet they have rl problems'
- 'Earning above 5K per year? Hmm i know someone rich who has cancer'
- 'She enjoys her baby? She is lying'
etc...etc.
Basically anyone who dares to smile for a second is miserable deep down/tacky/liar.
People just have different tastes, lifestyles, hobbies.
Anyway why is this different to those competitive threads: 'I'read 7 novels on hol', 'that's nothing. Me and dh read 9 each during a week in Italy'.
You could say the same about them, no?