You can use a OneMesh™ Wireless Router or Modem Router with several sets of Range Extenders or Powerline Adapters to create a OneMesh™ network. Be aware, you cannot create a OneMesh™ network between two routers.
Exactly, I have no clue why they have disabled OneMesh when you use another router in AP mode. That's like crippling the product. But if a router supports OneMesh, the range extenders become pointless so might be from a commercial perspective. 😝
It's just not about sentiment, Chinese Routers have some security vulnerabilities (Though not as much as Trump says). Another reason Chinese routers are cheap because they copy others designs & the firmware too. If you see closely, as soon as Netgear, Linksys etc. launches a new product you will see a copied chinese alternative next to it.