Originally Posted by Kapusta

MTBs tend to have longer top tubes and frame reach numbers than road/gravel bikes.

This has been true for many years but in recent years the difference has become even greater.

Go to any bike company's website and look at the top tube and frame reach numbers of drop bar road/gravel bikes compared to MTBs for a given recommended rider height

Several reasons for this:

1- Drop bars add a lot more reach than flat bars, so the frame reach needs to be shorter.

2- A longer reach frame with a short stem puts the front wheel farther out in front of you, which make the bike less endo-prone.

Of course, if you WANT an extraordinarily short reach.... then a drop bar frame with a flat bar will get that for you. But there are reasons that MTB designers and riders have long moved away from that.

OTOH, the fact that you feel like you can really rip single-track on your road bike (along with other comments you have make about suspension and single-track) makes me think that what you are calling single-track is not what most people mean by it.