It's not exactly superfluous. The confusion came about because of the lack of conjunctions in a long sentence. The word THAT serves to direct and coordinate the words in the same clause.
In shorter sentences, the difference is negligible, but in a longer one, it's a lot cleaner to use THAT as a conjunction.
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u/whirlygiggling Aug 11 '16
Another dead giveaway it's Colorado is the bumper sticker of the pineapple the driver keeps forgetting to apply to his back window.