Wayland doesn't require you to use GPUs. Only wl_shm is in the core protocol, you can build a software-only Wayland compositor without any hacks, with shared memory.
By the way, Wayland has nothing to do with drawing text, lines and icons. You just give Wayland a bunch of pixels.
That said, using the GPU for compositing is often better for performance and battery savings. It doesn't require anything fancy, GLESv2 is used by many Wayland compositors and is widely available, even on old hardware. It doesn't require proprietary blobs.
If one turns off special effects (compositing) and uses low resolution, even the cheapest mainstream gpu is sufficient to draw 2D text, lines and icons with 60Hz framerate. However, people expect to get more in graphics output than 10-20 years ago, so they buy high-res displays or turn on additional graphics effects in graphics environment - and then, we do need powerful GPUs, because those resolutions and effects require high computing power that is best to provide in a powerful GPU, not powerful CPU.
Many graphics cards/chipsets/etc. do accelerate 2D operations, unfortunately there's no feasible unified model of a "2D hardware accelerator" the way there is with 3D, so there's no unified support for it in kernel, either. The whole thing is inherently hardware-dependent.
Not anymore; at least not like they used to in 90's and 2000's. Today, they expose some overlays (and some limitations, how they can be used) and that's it.
There is a Nvidia OpenGL extension NV_path_rendering that was intended for accelerating 2d, but it wasn't widely adopted.
Also, I think today CPUs, even if fully dedicated to graphics, can't really compete with today high-end GPUs. Graphics processing and output is a highly parallelizable problem which GPU are designed for, but today CPUs are not .
By the way, Wayland has nothing to do with drawing text, lines and icons. You just give Wayland a bunch of pixels.
That said, using the GPU for compositing is often better for performance and battery savings. It doesn't require anything fancy, GLESv2 is used by many Wayland compositors and is widely available, even on old hardware. It doesn't require proprietary blobs.