bit rot

in just a few years, pretty much all flash websites and flash-based content will be inaccessible on modern computers (not counting VMs or flash sandboxes) because of dying support for the rather insecure tech (adobe flash has free() issues that make it the tech of choice for ransomware delivery)

all the creative programming efforts of people who used flash in the 2000s will be forgotten

doomed by their poor choice in proprietary software

Implying old versions of browsers don't exist.
And when your sister/mother/uncle will need to play their flash games or some flash-based app they will use it.
The tards at google and mozilla who think "stopping flash" means removing flash support are deeply wrong.
Browsers are Platforms like OSes: their value is defined by the amount of content they can access.(Yeah, muh games is also a valid argument, because people choose OS based on programs it can run it. Like videocards are sold for the purpose of crypto/gaming.)