Is this somehow distinctive from Dragon Magazine / Dungeon Magazine from the late 80s in a way I'm not seeing? Or eg. the various TSR boxed settings with dungeons?
I think Dyson's program is just a Photoshop extension and Dungeon Scrawl looks way more powerful, but it's worth pointing out the very similar timelines and styles.
That cross-hatching-in-the-walls thing is fairly distinct, and I saw it immediately on Dyson's blog but not on a quick survey of old Dragon/Dungeon maps. That said, Dyson is clearly going for that aesthetic mostly, so it could be convergent evolution, and I'm hardly up to date on current styles for maps in other places.
It looks like the person that made this program started playing around with the idea May 9 (https://twitter.com/probabletrain/status/1259172635776294912) a day after Dyson started tweeting about his program (https://twitter.com/DysonLogos/status/1258797586464542723).
I think Dyson's program is just a Photoshop extension and Dungeon Scrawl looks way more powerful, but it's worth pointing out the very similar timelines and styles.