Macs output whatever resolution you need. Mine is doing 1080i by just plugging in the monitor. Adapters are $20. Not sure what decade you’re speaking from.
Some newer Macs will do 1080, but not all displays support 1080, and so for many shows we run, everything is scaled to a 720 output. When you’re processing video signals, you want everything to be unscaled as much as possible, or you start running into resolution and cleanliness issues when you continually add and subtract pixels.
Unfortunately, most Macs I’ve used will not output 1280x720, they only have an option for 1280x800. And adapters don’t matter, they’ll do it whether I’m adapting to DVI or VGA. The video out method doesn’t really affect what resolutions the OS will allow.