Makie.jl only defines what plot objects are, it doesn’t know how to make images or vector graphics out of that information. The backends, CairoMakie, GLMakie, and WGLMakie implement different ways to turn the plot objects into rendered graphics, for example using the Cairo C library, OpenGL or WebGL.
You cannot use Plots.jl with Makie as nobody has written a working backend for Plots.jl that uses Makie.