I've been playing a lot of Minecraft lately because if you play with several chunks it consumes more cpu power it then consumes even more cpu power with shaders because it has to render more.
Yes, it needs it because the CPU supplies the graphics card with information
Generally: Yes, because the graphics card is supplied by the CPU with the information about what is to be rendered. The GPU then ensures that these come on the screen nicely. One speaks of a 'CPU-bottlenecked GPU' if the CPU is too weak for the graphics card and the full performance of the GPU can't be used.
Minecraft is an extreme case here, as the single-thread performance of the CPU is even more important here than in other games that were developed for multi-core processors and place much greater demands on the graphics card. This is clearly visible if you light a large number of TNT blocks as an experiment. The GPU is almost not needed while the CPU is running at full speed. (I'm talking about JAVA edition)