HDMI is shit. If you've never had problems with random machine hdmi port -> hdmi cable -> hdmi port on monitor you just haven't had enough monitors.

> Is HDMI seen as a “gaming” feature

It's a tv content protection feature. Sometimes it degrades the signal so you feel like you're watching tv. I've had this monitor/machine combination that identified my monitor as a tv over hdmi and switched to ycbcr just because it wanted to, with assorted color bleed on red text.