You can only say this if you haven't met people who have suffered from being hacked. Enormously painful stories. Flash is a trash fire, and Adobe and Microsoft externalised the penalties.
There is no reason we couldn't have had safe Flash except Adobe didn't care.
I've heard the Flash codebase described as a big steaming pile of C++. Perhaps they cared but making a secure Flash was an impossible task. Windows has magnitudes more resources working on it and it still gets exploits all the time.
They could have reimplemented it in a safe(r) language and runtime. It would have been a big effort, and Adobe extracted the maximum cash for least effort.
Comparisons with Windows don't make much sense because it is an OS and a thousand SDKs and ever growing attack surface.
I have huge amounts of nostalgia, from when my parents bought me a version of flash from my birthday to kickstart my whole interest in programming, to building animations and games for Albinoblacksheep - Without flash I would never have learned to code.
So yes, some people have nostalgia with no rose tinted glasses, and I would like to think I have a clue about technology.
There is no reason we couldn't have had safe Flash except Adobe didn't care.