> It's incredibly easy to see areas that have older ice breaks that have completely shifted due to later plate shifting.

That's not true at all as is evident from the article itself had you cared to read it:

"... to best reconstruct the motion of the surface, large areas suspected to be plates in previous studies had to be broken into smaller subplates along less obvious boundaries. This observation helps explain why some prior studies found that large plates did not reconstruct well or behaved in other unexpected ways..."

>Not sure why someone would write a paper on something that's already so well known and easily seen / understood.

Contrary to your claim, this subject is not well known, easily seen or understood and is why researchers continue to refine their models. The fact is that this is still a very new subject (plate tectonics via ice) with little data comparatively speaking. I'll further add that plate tectonics on Earth is still a subject that continues to be refined as new methods are developed, and more data presented.