Nitpick, but:

> Arduino literally opened their platform to competitors and flourished.

Arduino as a hardware manufacturer has collapsed in relevance in the last 5 years, in part because they were continually undercut by clones and similar/compatible hardware. In their case, it seems intentional, Arduino IDEs openly allow other manufacturers to add support for new boards. I think this was always the ethos of the Arduino project, so it’s hard to make a comparison to Prusa