Landscaping fabrics are by no means an answer to a no maintenance landscape. I know a lot of folks are under the impression that they can simply buy it, place it, cover it, and forget it. Forever.
First. There is no such thing as a no maintenance landscape. In many instances landscape fabric can make your life a lot easier. However, there is an upside and a downside to using it. And as with most everything else, proper installation and maintenance is required if you intend to use it.
Also, keep in mind that I'm referring to professional quality grade materials and not the flimsy products sold in do it yourself and home centers. If you're going to use that, you might as well use newspapers or cardboard boxes under your groundcover.
Landscape fabrics have their applications. They aren't necessary in all applications but might be preferred in regards to the type of groundcover you use.
Our company uses landscape fabric in 95% of the plans and designs we create. It's the nature of our business as we use decorative rock as the preferred groundcover around here. When using rock for groundcover and garden path work, it's necessary to have a separator between the soil and groundcover. Otherwise, you'll have mud rocks by the first rain storm.
In theory you should be able to use almost anything as a separator. I've seen do it yourselfers use anything from plastics to newspapers and cardboard boxes to old carpet remnants. Of course, as a professional, I can't use or even suggest something like this to my clients. You're on your own there.
Now personally, on any given project, I would much rather do away with fabrics altogether. I prefer to create living soil planting areas that are mulched and tended rather than being covered and forgotten. However, some areas are simply too large to apply this method and some folks just outright prefer to cover an area with decorative landscape rock.
Both mulched living beds and rock beds underlain with fabric will require some work to keep them beautiful. Neither is maintenance free. As long as there is wind, rain dirt, and blown in seed, there will be something for you to do in your yard.
When we create designs using landscaping fabric and rock, I make the client aware of a few things. 1) There will be blown in seed and dirt. 2) Something will have to be done about it to keep it from accumulating. I assure them that with the quality of fabric we use, nothing will grow in from the bottom. However, we have no control of what blows in on the top.
Spraying the unwanted weeds with herbicide will take care of the weed problem. However, this does nothing for the dirt, leaf, and plant particles that are hiding under your rocks. And if you allow these to accumulate, they'll continue to accumulate and you will never get rid of them. So periodic maintenance is required even if you do use landscaping fabric.
Periodically using a blower to clear out your bedding areas will slow down the accumulation of dirt and in some cases eliminate it altogether. How easy and thorough this is depends a lot on the type and size of rock you use.
Small pea gravel accumulates and holds onto dirt, and is harder to clean than rock of a 1 ½" + nature. Not only does it hold onto dirt but has a tendency to be blown all around when being cleaned with a blower. Pea gravel works well for paths, walkways, and smaller areas but I don't recommend it for covering larger areas.
As far as using landscape fabric under bark and mulch covered beds? In many cases this can actually be easier to take care of than living beds or rock covered areas as it can easily be picked up and replaced every few years. This will keep your landscape always looking new without having to blow dirt or mulch beds.
Remember. There's no such thing as a no maintenance landscape. Landscape fabrics can make things easier in many applications but like everything else, they require a little bit of keeping up. No, they aren't necessary in all landscaping applications. However, I believe you'll find them to be your best choice for many types of groundcover.