This is a stubborn misconception about learning that many teachers fully embrace. I’ve certainly been guilty of it over the course of my career. Early on I would’ve thought that discovery learning was ideal but it was just too time consuming to be practical. #education #teaching 
Discussion
If you’re following along, here’s the crux of the issue for me. Learners spend too much energy (their working memory) searching for solutions or even approaches to get to the solution for them to move anything from working memory to long term memory. 
I’m a bit confused, are you agreeing or disagreeing with the article?
I’m agreeing, mostly. As with most things in education there are few absolutes. And the article isn’t arguing that we should NEVER let students struggle through the discovery process. Just that the contexts in which that actually helps students learn are when students have most prior knowledge required to tackle the problem. Basically, not when students are learning new stuff but when they are applying knowledge they already have.
Ah, that makes decent sense. Much easier to figure a thing out when you have the basics.