I recall that was mainly a thing towards the end when the raid was escalating its nerfs. That's before mentioning the pre-patch of WoD where hard mode SoO practically became a slightly harder version of regular difficulty, for indirect reasons having to do with the squish and the classes.
Also I believe in this current Tier people misjudge the role of Gorefiend. Gorefiend is not just a boss. Gorefiend is practically the end-boss of half of the Tier.
It would be clearer what the role of Gorefiend is in the difficulty of the tier if the lower floor was simply another building. So, it's not exactly like SoO.