I think this is essentially a statistics thing; any online collection of people will tend to have a normal distribution spread from hate to love for the subject matter.

The person who hates it the most will fill an environmental niche when they see nobody has said it yet. But we have to work with the environment:

a generally-neutral comments section leaves only room to politely dismiss/critique one or two select aspects of a show.
a generally positive one allows people at the RHS ("LOVE") of the normal distribution free reign to gas it up, but only affords to the biggest hater in the room, enough space to say "well it was mid. It was alright i guess. It was overrated."
likewise a generally-negative comment section will see people who only disliked it start to convince themselves that they HATED it, while the few who LOVED it have to pretend it's "just alright" for fear of persecution

So now you see, U7826391786239 is a trailblazer; his negative-in-intent-but-ultimately-rather-ambivalent comment demonstrates typical no-man's land behaviour. With this comment he has spread his seed over the virgin soil of this online ecosystem and allowed the great debate to begin again on whether GoT is a good show or not