It's called marketing and they're pretty good at it. They do provide some useful tools however if you want to use them and don't just blindly follow the docs (which are selling you on things you may/may not need).
[0] Relay has its own spec and can be used only if the server supports it. Other GraphQL clients are either not well maintained or do not support as many features as Apollo does (caching, subscriptions are two features that come to mind)