I'm sorry, but you're mistaken. Framerate dropping below refresh rate is the typical and by far most common cause of stutter.
Stutter occurs whenever the frame delivery is out of sync with the refresh rate of the display.
What you are talking about may be considered a form of stutter, but is more often referred to as hitching.
No offense, but did you even read the paragraph you're referring to? It states the same thing I did, with the exception of using "stutter" for what is commonly known as "microstutter".
Screen tearing = Drawn frame being out of sync with output of the monitor. The picture is "split" across the screen, showing normally 2-3 different frames at the same time.
"GPUs render frames at varying rates. As the GPU seeks to synchronize with the monitor, persistent tearing occurs."
Microstutter, referred as "stutter" for understandability = Inconsistent drawtime of the frames, causing the image to feel sluggish even if the framerate is high and stable.
"Stuttering since the GPU might render frames at rates other than once every 1/60 sec."
Stutter, as normally referred in terms of PC performance = Complete stop of the video, likely caused by an issue in memory usage.
For stutter, see AngryJoes video @ around 39:54, and it stutters a lot in that particular area. I can't be bothered to watch the whole video again, but I remember them actually mentioning it while saying it's fixed in the latest build.
https://www.youtube.com/watch?v=lJpWBMH9EtQ
Please explain how my 144hz screen has anything to do with stutter, which ironically I never encounter no matter the framerate of the game. There is literally no difference in playing 60fps in 60hz or 144hz, except for a slight screen tearing.
It simply just refreshes the same frame 2 or 3 times, instead of once, but the time your eyes see the frame is not changed in any way.