That's true, but the problem is more with the fact that it's a pillowtop. You're almost always going to sink into something marketed as a pillowtop, whether it's also listed as firm or soft. Our mattress, for example, is listed as the firmer end of the spectrum, but the top is still a pillow that creates a divot after you've slept on it for a while.

I really hate this mattress...

What's really annoying to me, as I do more mattress research, is that there seems to be completely differing opinions on whether memory foam mattresses create heat, and whether they create more/less heat than traditional mattresses. I'm seeing mattresses with rave reviews and people saying they get no additional heat, with other people saying the same mattress makes them feel like they're a pizza in an oven.