There’s a difference between using closed-back noise-cancelling headphones in an office or plane and using open-back headphones or bone-conduction while riding a bike or running so you can hear vehicles and other runners/cyclists around you.
Open-back headphones are not just niche usage. They are also used for music production, watching movies at home (feels like you’re listening to speakers in the room with you instead of small headphones), and gaming (open soundstage makes pinpointing sound around you like footsteps more accurate).