It's better than gate-keeping with a personal set of rules to impose on others (when I know they don't even follow those rules, going from post history), while at the same time, wearing rose tinted glasses and ignoring anything else that was just as worthy, because it didn't fit their tinted shade specs.
Well, that's a deflection.
If someone's opinion on a game is purely based on seeing video of it, I'm generally not going to take their opinion on it very seriously in most regards (I mean they could have valid opinions on cutscenes and voice acting or w/e) and I think others are justified in being dismissive.
That is a perfectly reasonable use of "gate-keeping" based on a reasonable set of rules. If people aren't following them, then by all means, call them out when they don't.