pictures of babies/kids online?

Des • 2nd pregnancy due Feb17'! Back to back pregnancies- first baby will be 1yr old Jan 15 💗 #teamgirls
Hi Mamas
So there's a few ppl I know who don't ever post pictures of their babies faces like what is the reason behind it? Like they do they body hands everything but face. 
And so today I came across someone mentioning they don't post frontal pics of their kid online.... all is from the back side everywhere you don't see the kids face. 
What are the possible reasons? There is def something to it.....
It kind of weirds me out.