According to OP's website, Houston is a 15-minute by bike city:

and the core is 15-minute by foot:
Source (Archive)
Looking at Baltimore, it's even better, but it's a coastal city, so that's to be expected.
On foot:
For comparison, these is the actual proper city borders:
I tried to get the screenshots to line up, but the beltway in each screenshot is a good reference point to compare.
But yeah, looking at that, basically huge chunks of the city are 15 minute walkable neighborhoods.
Hell, when we add bikes into the mix:
The whole metro area including all the surrounding suburbs are easily 15 minute neighborhoods by bike.
I know this has been obvious the whole time, but this is clearly about something other than actual urbanism. I think it's probably 65% about aesthetics (redditors wanting to live in an episode of Friends) and 35% about politics (ie self hating americans).
I don't drive (epilepsy), so my whole life I've had to deal with public transit and cycling and walking and stuff like that. Sometimes it sucks, but in general, living in an east coast city, you can get around decently enough.
I couldn't live out in the sticks, so I moved to somewhere more accommodating of my condition, which is the city.
Urbanist dweebs really just want to impose their goofy fantasies about sitcom urban living onto random midwestern towns, instead of saving up their money, nutting up, and moving to the already existing urban places.