Does Play-based learning actually work?

Something I've noticed in my college experience is that sometimes, schoolwork can make students feel miserable. However, I have yet to decide on whether if that's actually a bad thing or not. Is schoolwork meant to be difficult, but rewarding at the end of the experience, or is it supposed to be fun? Can it be fun and also rewarding at the end of the experience? An article I recently found on T74 advocated for more "play-based" learning within elementary schools and I personally have some reservations for their ideas, but at the same time, I believe that their suggestions are for the correct motives.

The main purpose of the T74 article was to advocate for more, "...guided play and a playful learning approach in elementary schools", because, "...it’s playtime that prepares students for classes like math and reading, Hirsh-Pasek said: Learning how to play teaches collaboration and community building, which aids language development through listening and talking". They even included research results such as the below:

Source: https://infogram.com/how-preschool-affects-gpa-1h7j4d7zqeed4nr

1. Academic experience is the traditional worksheets and lecturing styles of learning. Graph shows worse results in 3rd/4th grade.
2. Child-initiated experiences include guided-play and playful learning. Graph shows improved results in 3rd/4th grade.

Even though the logic and results in this article "add up", I still have my reservations. If educators make learning more "play-based", would there be an abrupt transition in older academic years? By this, would "play-based" learning be so ingrained in students that they would only expect work to be "fun" when in reality, work is difficult? In order to eliminate this transition, educators would have to make education "play-based" through all of high-school and maybe even college! Even then, students would realize that sometimes jobs are stressful and tedious. 

In my opinion, "play" is an important concept at younger ages, however, we should guide children to both playing and working hard. We should let them know that playing is an important component to learning social skills and gaining valuable collaboration skills while working hard is a requirement for success. The emphasis should be on creating a good balance.

You can find the article here: http://www.the74million.org/article/a-new-push-for-play-based-learning-why-districts-say-its-leading-to-more-engaged-students-collaborative-classmates-and-better-grades/

Feel free to express your opinions in the comments section below!