Rating is subjective.

It's how you feel about a show. The feeling you experienced watching the show. That might change after watching all of it. But even if you only see a couple of episodes, you can decide how you feel about the show and share that. Because it's your experience.

It's a rating system, not a systematic review or critiquing system.

Quite frankly, is it really possible to discuss the show made you feel using only the numbers 1-10?

I don't think so. But the rating system is for people to get a quick (not thorough) look at what (a lot of) other people think. What most other people think might not always be the same as what you think, so don't stress about ratings too much.