Yes, and component memoization (and PureComponent and shouldComponentUpdate) only prevents re-rendering of the component's descendants. But every component that uses a context value will still re-render every time that context value changes, which could potentially be way too many.

For example, if every Cell component in a big Table component is using the same context value, they will all need to re-render when any cell value changes, regardless of whether the Cell component or some of its descendants are memoized. This is a common pattern in Redux, which solves this problem and will only re-render the Cells which are using cell values which have changed. Recoil would provide the same benefit.