Unigene Heaven was released in 2013, when tessellation was state of the art. Games have moved on.
Generally the low end cards are targeted at lower resolutions (720p,1080p), while higher end cards are targeted towards higher resolutions (1440p, 4k). Ideally, a buyer would still be able to game, just at a lower resolution. A person seriously contemplating gaming on an imac would gravitate towards those higher resolutions, so a test at 900p contains no useful information (except, perhaps as a apples to apples comparison, which wasn't made.)
Still, the 5300 test tells me that my own card is getting long in the tooth.