They have made no reference to the amount of years which they are talking about, simply stating "kids jump into relationships too fast" is correct, and if they're teenagers then they were around at least 13 years ago, when they were born. So they could mean "When I was 10, I wasn't in a relationship - but kids today are." Let's remember that teenagers can be 19; so they can see a clear difference.
They aren't saying that anything was different before, just commenting on what is happening now.
I'm talking about when they're comparing things to some mystical time in the past, key word "nowadays." Because I hear people doing that all the time
this doesn't apply to music, before anyone starts