You've just answered your own question
The biggest limition of freesync has always been it's refresh range - which becomes a big issue when you are looking at higher end panels (1440p and 4k in general) where your FPS is very likely to be hugely variable and to drop below 60. I agree that they are pretty much at feature parity *at the moment* and you can indeed find high quality IPS panel FS montiors that support the full ~25-240hz rangebut FS has lagged behind for a long time, it only recently that the tech has caught up.