Dr. Peter Gray, a professor of research psychology who's studied the role of play in human evolution, is my favorite expert on this matter. He's the author of "Free to Learn: Why Unleashing the Instinct to Play Will Make Our Children Happier, More Self-Reliant, and Better Students for Life." In his work, he makes the crucial distinction between “guided play” and “free play.” He argues that kids today get plenty of guided play from parents, teachers, and coaches but not nearly enough free play by themselves and with their peers.
Guided play is what you're describing in this particular situation as the teacher controls the parameters and has learning goals in mind. I imagine that she has aims for each center, whether it's exploring math manipulatives, building with blocks, or creating with art materials. While guided play is certainly a developmentally appropriate practice for preschool, it shouldn't be a substitute for free play according to Dr. Gray.
Free play is his passion and he champions it in his speeches, books, and articles. With free play, children are in control and are led by their own unique curiosities. Unlike guided play, there's no adult interference. As such, it builds a youngster's independence, initiative, and self-confidence.
Dr. Gray's research explores how free play has decreased significantly in the past 50-70 years with a corresponding increase in depression, anxiety, stress, narcissism, and suicide among children and teens (I would also include obesity). The decline of free play has also been marked by the decline of social skills, empathy, and creativity.
You may be interested in my article entitled: “33 Reasons to Choose a Play-Based Preschool, Not an Academic One.” https://wehavekids.com/education/Preschoolers-Lear... It includes a fantastic video of Dr. Gray doing a TED Talk about the importance of free play.