I think it's because Vue is opinioned, just like Rails, therefore dev's happiness(?)&productivity is one of the main goals of these frameworks. In case of React, there are a lot of libs you can choose from, I'd probably use React in more heavy JS application - think some games or something like draw.io (don't know how to call it). To be honest, I don't have enough experience to back up my claims, so take it with a grain of salt.