alt Hacker NewsIt's not pedantic, it's just the way it is. For OSM to be valuable it needs to be consistent. There are many tags available but the "you can't walk here" tag is about whether you have a right to walk there. There are many highways you wouldn't want to walk on, but there are other tags to indicate that, like speed limit and presence of footpaths etc.
Saying a path can't be walked has pretty large consequences since routing apps will refuse to use them for walking directions. A highway with no footpath does seem extreme enough to warrant refusing to route for walking directions, but otherwise it's best to not block walking unless it's literally impossible or illegal to walk there.