You learn a lot building something from scratch. And it&#x27;s fun. You start with naive, clean abstractions and slowly encumber them with trade-offs as you make progress. That&#x27;s a fun Saturday for a lot of us.<p>There&#x27;s a massive difference between that and tackling some long-tail issue on a massive, mature project that apparently wasn&#x27;t trivial enough or fun enough for anybody else to tackle. i.e. work.<p>Asserting they could&#x27;ve spent that time contributing to React is like suggesting they could&#x27;ve used that time volunteering at the homeless shelter peeling potatoes and doing jumping jacks. Energy and interest just don&#x27;t work like that.