The hardware is the least important bit of Arduino.
It’s the IDE, as crappy as it is.
The "batteries included" nature of their IDE is remarkable for getting up and running with any random hardware that's meant to be arduino compatible.
Like, you can install support for a board or some hardware and have premade example code running on it within a few minutes. Without even reading any extra documentation.
The IDE is absolute dogshit. IMO they should pivot to contributing to PlatformIO instead to keep this awful IDE going.
Not even the IDE. Those of us that care have switched to VS Code + PlatformIO. The arduino ecosystem is all that matters, and that won't die for a long time. Heck, there are many chip manufacturers building in an Uno header pinout into their dev boards so you can try them out with off the shelf Arduino shields.