My money is on angry tennis players who damaged the nets.
If anything, Pickleball players are open and inviting. That's why the sport has grown so fast in the last few years.
It's been around since 1965!
Name me one sport that the opposition complements you on a 'good shot'... All other adversarial sports are out to 'get' the other team. Even in tennis! Sure they're all pals after the game, but during the game they're out to win it. Pickleball is different. Sure, winning is ideal, but having fun is the goal.
The 'problem' with tennis players is they think their shit don't stink! Tennis is a high brow hoity toity English sport that has spread about the world. Pickleball is the new kid on the block that's taken over precisely because you don't have to spend 20 years of your life mastering it. Anyone can successfully learn the sport in a few hours.
It's akin to ping pong (table tennis) and instead of standing next to a table, you stand on the court. You have a paddle and a wiffle ball with 2 to 4 people on the court. Same as tennis.
The rules are similar, sort of. The difference is that you can put 4 pickleball courts on one tennis court. Those who play tennis, as well as racketball & squash tend to have better skills than most (any wonder?).
There are 5 tennis courts near me and they're rarely used. There also are 4 pickleball courts (same space as 1 tennis court) that are continually in use. With 5 tennis courts you can service 10 to 20 people. At any given time 4 pickleball courts will have 8 to 16 people playing and 8 more waiting to play! 'Doubles' are more likely than 'singles', so 16 is closer than not. Tennis typically has 2 players on a court.
Pickleball is the 'new internet' whereas tennis is the want ads in the newspaper. They don't know it yet, (or maybe they do?) but tennis is going to be less popular in years to come.
Y'all should try it sometime!