BIOS can only manage VESA which is much much slower than the capabilities of a modern GPU, so they might have meant graphical performance in regards to that.

VESA BIOS Extensions support direct framebuffer access in protected mode, and I don't imagine the lack of accelerated 2D operations would be a practical bottleneck when implementing NES-style graphics on modern PCs.

UEFI GOP additionally supports accelerated bitblt, but again YAGNI for 2D game performance at reasonable framerates on a modern PC.