I have many nerdy friends who have been Linux users for ages. But most of them don't know such a thing as Openwrt exists or have never bothered to give it a try.
It's a very fun piece of software to play with and can be extremely useful for routing traffic.
Wondering why it isn't more popular/widely used.
IMO, I'd run pf/opnsense on an x86 box, but openwrt on a low powered device...
Did that years ago with a pfSense firewall connected to the DSL modem, with OpenWrt APs around the house...until the hardware couldn't support the next version of OpenWrt... (not enough RAM?)