This is because some old computers don't support too high resolution and can only be suitable for VAG analog signals, so there is only VGA interface on the display. Now new computers generally have four modes: VGA, HDMI, DVI and TP. The latter three modes all support high-resolution digital signals, so they will choose HD, and there are graphics cards above the medium level, all of which support high resolution, generally only HDMI, TP and DVI. So you can understand why this is so.
I hope it will help you, and I wish you happiness ~ ~