Why does the WRITE-HOST in the tiny script make the output flicker?

Here is a tiny reproduction of a screen output issue I am having. I guess I don't understand why this flickers since I am repainting the same pixels each loop.

Thanks for any suggestions

Function CoordinateXY
{
 Param([Int] $x, [int] $y)
 $Position = $host.ui.rawui.CursorPosition
 $Position.X = $X
 $Position.Y = $Y
 $host.ui.rawui.CursorPosition = $Position
}

cls
while(1 -ne 2)
{
 coordinatexy 10 10
 Write-Host -NoNewline "why am I flickering"
}