Yeah, that's pretty much it. The counterarguments don't address what AstroBen noted.: newbies get high gains from any kind of stimulus. The paper has simply confirmed the common knowledge teached in universities.

The problem is, after you are no longer a newbie you may train for years with very little progress, and that's when you need to start differenting stimulus, being strategic about it - otherwise you may stay stuck.

And unfortunately the paper doesn't address or refute that, while it's coverage (or even the title of this hackernews) may suggest otherwise.