I want some opinions

So yesterday I went over to my in laws house to visit and I saw a swing there similar to this. I thought it was the cutest thing ever but apparently my sister in law who just had a baby freaked out on her parents for putting her 4 month old in this because she said her doctor told her specifically not to use these swings because it's not good for the baby. Now I'm 38 weeks pregnant and me and her brother bought one for our baby and never heard anything bad about these swings because everybody and mother has used them since the beginning of time. I'm happy his parents did get one because the times I came over there his sisters baby is always on the floor and there is dust and dog hair everywhere. The dog has almost stepped on him. The poor baby has a bad eye infx too.  I don't get it. Maybe it's just me but I did go online and did my research and it just said something about leaving the baby unsupervised due to risk of SIDS. Now I want your guys opinions what do you think?