The inclusion of players zooming by on brooms was a fun way to end a dramatic scene of triumph for the focal character. The Quidditch pitch is far from the school and having players in the distance wouldn't have been as exciting.
But reminding the audience of Quidditch may also be important for upcoming films. Responding to a 2018 interview with The Leaky Cauldron, series director David Yates says that the revisits are more than just fun:
"I don’t think [Rowling] is really interested in repeating herself or leaning too much on the past. [...] Going back to Hogwarts is a very important function of this story, not a sort of way of appeasing the nostalgia factor of the series."
Later in the interview, he does seem to concede that the Hogwarts scenes also serve to reconnect viewers with the familiar world of Harry Potter.
Yates said this decision actually came as a result of wanting to give 1920s Dumbledore a proper introduction, and more of an idea of what to expect from the Hogwarts flashback scenes:
"It was something that evolved in the developing process. Because we
were introducing Dumbledore, it felt right to bring that world back
into this one. We’re there very briefly."
Whether the Quidditch players were simply for dramatic effect or will be important later is still unknown. In universe answer: Those were Seeker tryouts, and all the potential recruits were eager to catch a rogue Snitch.