The point is that we know pretty little about a cat's true way of thinking, but they do at least know that cats can indeed love their owners pretty much, and also care for them more than humans give them credit for. I've seen the prove of that when my cat was beyond herself of happiness when I came back from surgery.
Cats only have a different way to express themselves than dogs do. There has been a writer who wrote two books about psychological impairments and compared them to animal behavior. She compared Asperger to cat behavior and ADHD with dog behavior. Well ADHD is known for hyperactive behavior, but I cannot say I know too much about it. When it comes to Asperger, I know a lot more, and then I can definitely see why this writer compared cat behavior to that. People with Asperger, or with an Autism Spectrum Disorder in general, can also give you the impression they don't care about you at all, while deep inside, they can love you more than anyone can, but you just have to look beyond their apparent behavior to discover that side. Cats are much the same in that perspective.
Now I must also say that cats have a bit of things in their "language" that may not really be interpreted as "love" to humans, like turning their backs to you without looking at you. It means a lot though if a cat dares to do that. In the wild cats may be predators, but are very low ranked in the food chain so they keep track of everyone who is close to them. The fact they are not keeping an eye on you means they trust you completely that you are not gonna do crazy things. If you understand the logic behind this, you can see a different side of cats.
I do not know of cats do love their owners more or less or as much as dogs do. All I know is that they do love and care for their owners, but that they have a way of expressing it that humans do not always interpret correctly.
