Is this true about babies learning to crawl and walk?

So I was out and about today and I had a lady ask me how old my son was and I said 4 months and she started asking if he rolled over yet and I was like only a few times but yes but when hes on tummy time hes acting like he wants to crawl and I was all happy about it and the lady rained on my Parade because she asked it he had siblings or was in daycare and when I said no she said then he probably will be a late bloomer because babies who aren't around other kids or motivation to move around tend to not want to crawl or walk as early as those who have siblings or go to daycare... and I was just like oh I didnt know that and now I'm just wondering if I'm hindering my son from getting better mobility because I wanted to be a stay at home mom for his first year.. is what she said true tho??