it hasn't even been 1 year since RX590 came out,
but Anti-lag for Dx9 is exclusive to rx5700 series,
while nvidia made available for all their gpus.
Nvidia released Ultra-Low Latency
Our new Low Latency Mode is being released in beta with support for all GPUs in DX9 and DX11 games (in DX12 and Vulkan titles, the game decides when to queue the frame).
Most of the Free To Play online First Person Shooters are in Dx9,
I am hoping that AMD can enable or cook a driver to make anti-lag work for dx9 titles in Polaris.