Question about Burmese cavalry archer

Hello, there is something that has been baffling me of late. Can you tell me why Burmese cavalry archers are fully upgraded except not getting thumb ring?

I dont know how exactly accuracy calculations work but it seems to me that 50% renders then completely useless in anything but mass battles.

Is this how the Dev's intended for it?

If you dont mind, I would humbly request that you mention your de elo in your answer so I would know how much weight to place in your opinion.