"WPA2 has some problems. It allows anyone with a bit of software to boot people off a Wi-Fi network with a DEAUTH attack. And it's not particularly secure."
I was a little surprised to find that the Cisco Meraki wireless kit in work takes advantage of this. Pretty much, you get a list of every wireless network "nearby" yours, with the option to "quarantine" it. If you do that, your own kit performs de-auth against any nearby clients trying to join those networks, which results in only "your" networks working and everything else literally disconnecting for everyone within seconds.
Obviously, being an unlicensed channel, this is possible but I was more than a little concerned about the legal consequences of such things. Being a large school, our site is in the middle of acres of fields, so we only ever see our own network and "rogue" networks trying to pretend to be ours (usually the kids trying to fool their friends) or things like public wifi from nearby coaches. But I was quite shocked that not only is it possible to easily block foreign SSIDs from even operating, but that this is sold as a feature (Air Marshal) that you can apply to ANY SSID you don't like, rather than just those trying to masquerade as your own.
It is, however, quite effective... if you set up an Android phone as a hotspot on the site, you'll find that no device is able to connect to it for more than a second without getting kicked off by the site-wide wireless. And, yes, the logs literally tell you that it basically performs a de-auth attack to do that.
If WPA3 does indeed find a way to stop this, I imagine that they'll find some other way to do the same, but still... it's a scary thing to have as just an advertised feature on a common managed wireless product. If someone did want to be malicious you could easily kill the wifi to an entire swathe of offices, houses, etc. in minutes.