To me dated is a bit different than old fashioned. I would think it meant stuck in one time period. So like Jennifer or Jason might feel ‘dated’ to the 80s. But old fashioned to me would be further back than the 80s, names like Eugene or Edith. So I would say if you saw a young son and his dad and got told they were Gary and Alfie, you’d probably know the dad was Gary and the son was Alfie, because Gary is quite dated. Whereas if they were James and William it might be harder.
Personally I don’t mind if a name is a bit dated but some people prefer a more ‘classic’ name that sounds quite timeless - something possibly like Thomas or Grace. I like lots of names considered ‘dated.’ I don’t think Chloe is particularly dated though - not in the way a name like Sharon or Tracy seems dated to me. Chloe feels more versatile to me!