One thing to keep in mind when comparing older mtb frames with shorter top tubes to newer ones with longer top tubes is that the move to longer top tubes also came with a move to shorter stems. So overall, the reach to the bars is not necessarily longer.

When people talk about MTBs getting “longer” what they are really refering to are
1- the longer top tubes (that usually come with shorter stems)
2- longer bottom bracket to front wheel distance, which is a result of the longer top tube and slacker head angle.

And “lower” refers to the bottom braxket hieght.

None of these things really increase the reach to the bars.