Every three months might be too often for a tool like curl. In case of React, the community seems to be happy with the tradeoff between moving forward and keeping the old code working.
You might want to ask a few people who use React to draw the conclusions. I talk to a lot of people in the React ecosystem, and so far the feedback I heard is that updating React has been the least of their worries, compared to some other libraries in the ecosystem which are far less stable.
Personally, I updated a fairly large (~1000 modules) app from React 0.11, to 0.12, to 0.13. After the ecosystem catches up and libraries release compatible updates (if they need to), it always took less than a day to upgrade. Doesn’t seem like a big price to pay for avoiding stagnation and actually improving the library.
And I wasn’t even using codemods which React team ships (and widely uses internally at Facebook). Codemods just convert your code through most of the API changes automatically.