I'm not arguing that the C8 specifically isn't fine. Just because you can list one display that scales up well doesn't mean that most of them do. A lot of displays are absolutely terrible at rendering non native resolutions.
Either way, if you're serious about perfection then you should own the best displays as well! Even if you can't afford that, the lower tier displays handle 1080p beautifully so it's a non-issue.
Do you have a specific TV in mind then? I feel like you must have encountered a shitty 4K TV with a poor scaler and high latency to make that comment.