> It's a Windows graphics server telling a Windows client how to draw some Windows widgets
In the 90's when everything was made of lines and rectangles, you're right that this deep integration made RDP perform much much better.
Now though, nearly all applications are composited bitmaps (webviews, opengl surfaces, etc). There isn't much scope for sending the raw draw calls over the wire anymore, and instead using some video codec to send the surfaces as bitmaps, and then compositing on the client is about the best you can do.
In the 90's when everything was made of lines and rectangles, you're right that this deep integration made RDP perform much much better.
Now though, nearly all applications are composited bitmaps (webviews, opengl surfaces, etc). There isn't much scope for sending the raw draw calls over the wire anymore, and instead using some video codec to send the surfaces as bitmaps, and then compositing on the client is about the best you can do.
VNC doesn't even do that though...