I think Adobe should have open-sourced the Flash player like 20 years ago.

If they had done that, then it could have been incorporated into the web standards (or at least something somewhat inspired by it). Instead it took like 10+ years for web standards to catch up, Flash Player got crappier and crappier and eventually murdered in 2020.

If they had FOSS'd it, Adobe could still be the de facto leader of web-authoring tech.