We don't have any reason to believe otherwise. His results are from wounding and minoxidil. But I think we have to look at it from this point of view:
2young2retire wounded with a 1.5mm roller I believe, and he pushed it to the limit. He probably ended up getting the needles in farther than the 1.5mm just from how hard he pushed it into his skin. And as I'm sure a lot of you know, rollers end up making wide "pit" type wounds instead of precise vertical wounds like a pen/stamp.
the reddit user (I forget his name on here with a bunch of numbers, I'm just gonna call him "7" from now on) used a pen at 2.0 mm, so slightly more depth than 2young. He also passed each area of the scalp a total of 6 times in one session - twice vertical, twice horizontal, twice diagonal. Pretty thorough.
I think there is a correlation between 2young and 7's results. Both methods induced a heavy wounding response. I think that with the pen you are less likely to bleed if you wound thoroughly due to the precision of the wounds. However if you are using a roller, you will bleed if you wound thoroughly with a 1.5mm roller. Either way, those that wound thoroughly seem to have the best regrowth.