My plan is to keep garden fabric on my vegetable garden year round to keep the weeds down (especially in the spring before planting) but my in-laws claimed it's bad for the soil. I would put the new garden fabric down covering the whole garden in the spring, then cut holes where I plant. Then after harvesting I'd leave the fabric in place over the winter. Then in the spring throw away the old fabric and repeat. This would allow me to avoid rototilling also.
No, provided the 'garden fabric' is water and air permeable and not thick plastic. Geotextile fabrics are commonly used in areas with existing planting, usually with some kind of decorative mulch on top. If such a membrane were laid with stones on top and left for some years, it's likely that the area would need to be improved by digging over and incorporating humus rich materials before any planting takes place.
It would be much better for the soil, though, if you used organic mulches instead, a good two or three inches deep, without a fabric - these would break down over time and improve the soil, adding humus, whilst suppressing weed growth.
I note you have altered your question somewhat, so here's a bit more to respond to that. Sounds like a nice idea, doesn't, easy peasy, what you've suggested, but as others have said already, it's an imperfect solution. Persisent weeds will come up through thinner fabric, and others, grass particularly, may well root through the fabric into the soil beneath.
The other thing to consider is this - if you are growing edible crops year on year, you will need to incorporate various nutrients in the soil annually, or your crops will be poor or nutrient poor. One tomato is not necessarily like another tomato - one grown in nutrient rich soil teeming with bio diversity, minerals and trace elements will provide much more nutrition to the human consuming it than will one grown in a soil that is depleted. (I use the term tomato loosely, it's just an example for any vegetable/fruit.)
If you want a labour light solution, then spend your money on organic origin mulches instead - this will break down into the soil and you won't even have to dig it in, if you add it yearly. At a depth of 3 inches, it will suppress weeds pretty well - which type of organic matter you use may vary depending on what you think you want to grow the following year though - root crops like carrots aren't keen on soil with a high animal manure content.
What kind of plants are you thinking of growing? I ask, because you mention keeping the weeds down in spring "before planting". If it is an annual bed or a vegetable bed that you will be replanting every year, landscape fabric may not be your best option.
If it is a vegetable garden, every veggie you plant will have different spacing requirements, and you should plan to rotate them around the garden to keep the soil healthy. This will be difficult to do with fabric, since you need to cut a hole for each plant in the garden (unless you are just using the fabric to cover the paths between rows).
If it is an annual ornamental garden, you'll need to find a way to keep track of where the holes in the fabric are, so you know where to plant each year - and you'll need to replant in the same spots, so you don't have holes all over the fabric.
In either case, I agree with bamboo that you should really consider several inches of organic mulch instead. From my own experience, I have some beds with high-quality contractor-grade landscape fabric, some with big-box "contractor-grade" fabric, and some with just layered cardboard. All of the beds are covered with organic mulch (some years I use woodchips, some I use leaf mold). I have slightly less weeding to do in the beds with the true contractor-grade fabric (purchased from a landscape supply company) than I do in the beds which were covered in cardboard and then mulched. The cardboard was free, so for all beds from now on, I'm going with cardboard. The worst beds are the ones in which I used the big-box store "contractor-grade" fabric. The weeds come up right through the stuff, and are very hard to pull, because their roots get all entangled in the fabric. I am in the process of ripping that fabric out completely - it was a total waste of time and money.
Organic mulch is very good stuff. a thick layer of grass clippings is good for keeping down weeds, and adds nitrogen to the soil for the growing plants. I use it for my broccoli plantings with insanely good results, even in hard, poor, untilled soil. It will also pull you right through droughts without trouble. The biggest drawback with grass clippings is appearance. You can cover it with a sprinkling of straw or wood chips or whatever blends well with the surrounding landscape.
I have done the same thing for the first time this year. I prepped my new raised planting beds a month ago and covered them with landscape fabric until Memorial Day. I will add more soil and nutrients and turn it them over again when I uncover them. I don't expect there to be any problem. After I plant the started veggie plants, I will use Preen for the summer. This will also be the first year I ever used Preen.