GPUs aren't really designed for 2D graphics out of the box. I've written about this before [0].
Text rendering can be tricky, but not that much trickier -- it's just the same curves at smaller scales.
Not sure what you mean by stencil textures. Are you talking about the NV_path_rendering approach where you stencil out the path? Yeah, that's not really a thing that people do these days.
It's not that simple unfortunately. Hinting for TrueType fonts is a thing and without properly aligning resulting pixels at their own scale fonts tend to look very ugly when following pure curve definitions. Oversampling at e.g. 8x size is one possible option but then there are other problems that pop up once downscaling to display size.
Fast, efficient 2D graphics using the PostScript (i.e. SVG) rendering model is still an open research problem. Most shipping implementations these days do full tessellation to triangles on CPU.
You have to do things like stencil texture to speed things up etc etc.