I have played on NA during HW where the NA servers were still in Canada. They were horrible, terrible servers, and some weeks it wasn't unusual to have stuttered micro freezes every couple of seconds in dungeons, which was absolutely miserable to play through, with abilities refunding themselves half the time, the server telling you "nope", then proceeding to rubberband things back and forth.
I have played on NA during SB where the NA servers were moved to Sacramento because the ones in Canada were just bad, since I am in Europe, latency that used to be around 80-100ms on a terrible server jumped to 180-200ms (170-180ms with a VPN). Here latency could be felt, as in just the time for information to go between me and the server, which made mechanics tighter to deal with (on EU right now I can dodge AoEs even after their telegraph visually go off for a microsecond or two, I had to preplan at 200ms, and it wasn't unusual to be caught into one even though I was visually out of the telegraph before the snapshot). I also happened to play SB MCH which was infamous for how ping sensitive it was, I raided with it, and constantly trying to improve my latency and experience, I tried many VPNs, and eventually noticed that with the exact same ping, I had a 1 to 2 second difference in delays between my opener executed in an encounter instance and my opener executed on a dummy in housing wards. 2 whole seconds lost in encounter instances over a 20s opener, while I could actually perform the low ping opener just fine in housing wards? That made no sense to me until I understood it may be a matter of latency when it comes to mechanics and dodging AoEs, but it isn't when it comes to the actual battle system, where everything is embroiled into animation delays, server delays, ghosting, and bad netcode.
I moved over to EU servers for ShB, have between 20-30ms of latency now, and I can certainly see the difference but... Sometimes we just get rotten instances out of the blue. Especially in pvp just to drive me crazy, after many perfectly fine games, I'll be suddenly handed an instance with gigantic freezes every 5s, where everything stops moving for 5 more seconds until everything resolves at once, again and again and again.
I wouldn't be too quick to judge. XIV servers, or netcode, or whatever it is, can just decide to not play nice, depending on the player, their connection, or just the battle system itself. Like, can anyone seriously tell me with a straight face it's normal that housing wards could suddenly work perfectly fine like I was playing just next room to Yoshida's office, when duty instances played like I was playing from the moon?