Just to add to the anecdotes.. I regularly run RDP over VPNs and web gateways all over WiFi and only occasionally feel a little bit of lag, otherwise it's so fast I forget it's not my local device. I largely use CLI's, IDE's, Office, web browsing, and often tell myself off for watching YouTube videos over the RDP connection instead of locally.
i use rdp over zerotier and it works like magic. the "server" is having a 30mbps connection so i'm limited by that. still, the experience of over 15 concurrent users is not bad.
i do excel, word, Libreoffice, firefox, heck employees even watch youtube on firefox over rdp and its "slightly" difficult to have it desync video and audio sometimes but it works.
my only problem is getting rdpwrap to patch every 3-4 months. i run ltsc so i should be getting less updates but what do you know, it messes up and all hell breaks loose.
Huh? Something must be seriously wrong with your network. I did everything via RDP (including watching movies) for years, over ADSL, with no issues whatsoever.
Is it? Even on gigabit LAN there's a noticeable amount of latency. For web surfing it's mostly passable, but for text/code editing it's very annoying.