Absolutely nothing is *essential*. Anything that says otherwise is just trying to sell products.
All of the items out there have a certain usefulness. As you read in this thread, some people found that a particular item was "essential for them" -- but that's a subjective, personal need, not a generality. Other people do just fine without that item.
Even stuff that most people would say are the absolute basics, you don't really *need*. There are ways to not use them. That's not to say they don't come in handy. It's a matter of semantics... if the ways to not use them would be terribly difficult for you as an individual, then go ahead and use them. They're just not *essential*.
You might be interested in a series of blog posts I wrote, "Baby Essentials That Aren't.
I address more than just 'furniture', but the whole point of the series was to question the automatic 'need' for various baby items.
You don't need
diapers, you can EC. You don't need
a crib, you can co-sleep and/or use a floor bed. You don't need
a stroller, you can babywear. Etc etc. And you don't need a nursery at all -- just a room that can eventually be theirs when they're old enough to actually appreciate it.
Really the only thing I would suggest for almost every mom as an essential is a sling (or two or three) of some kind. It serves to replace several "furniture items" and is better for baby's development in so many ways, anyway. Once you've got that down, then everything else is just a matter of personal preference!
As for what we used... slings. Got her a toddler-bed (well it's actually bigger than a toddler, but smaller than a twin, it's an IKEA child's bed) for a safe place to sleep on her own once she was a bit older, side-carred it at first, moved it across the room when she was about 20mo, then into her own room just passed 2 years old. Had a bouncy chair, which was handy for showers, but I also took her in with me in a water sling. Didn't use it overly often.
We had a potty (Baby Bjorn Little Potty) for EC. We had a stash of cloth diapers, and training pants, and undies, kept in baskets. Put her clothes in a spare drawer in our dresser until she got her own room.
We used a high chair, but in hindsight I think we didn't even need that. Ours was very simple, none of these 3-reclining-positions garbage jobbies (I mean, WTH? You're not supposed to do solids until the kid is old enough to sit up on their own, it's a major safety hazard to recline a baby while feeding! What's supposed to be the purpose of these?) But when we moved, we switched to a booster seat at the table, and found that just as easy as the high chair had been, and one less big piece of furniture to have around.
Oh, and it isn't "furniture" but you don't need baby food either...