Oh... something I am a real expert at! You are mixing your context when calling vines hybrids. There are three ways you can grow grapes for fruit. 100% original "own rooted" vines, grafted vines and hybridized vines.
Let's back up so I can explain why that is. Many Americans in the 1600-1800s tried unsuccessfully to bring European vines to North America and they always died within a few years and they could never figure out. When American vines were brought to France in the 1860s to study the differences between American and European vines, they inadvertently brought a root louse called phylloxera with them in the soil (they also brought over powdery mildew, but that's another story).
As it came to be, phylloxera completely wiped out most vineyards in Europe within a decade or so. Then started a race to figure out a "cure" for this bug. Three methods were attempted. The first was to drown the soil in chemicals to kill the bugs and that worked for a long time. Some vineyards were still operating like that until the 1960s.
After more research, they figured out that American vines were resistant to phylloxera. So that led to the other two ways of keeping their vines alive. Hybridization between French and American vines. These hybrids were resistant and yet made drinkable wine. Not the same quality as 100% vitis vinifera but hey it got you tipsy just like a good Cabernet did. Many of these hybrids are still around. I have grown several of them. One that I liked a lot is called Leon Millot. The French after WWII, in a fit of purity, have banned most of these grapes and had them ripped out.
The third way was considered the best way to preserve the flavors of the cabernets and chardonnays of the world. They took a page from the apple growing industry, which had already perfected the art of grafting roots onto a different tree. So, they grafted American vines onto French (and German and Italian and so on) vines. This worked out almost perfectly for everyone. In fact, because they use several different vitis species (there is only one vitis species in Europe, vitis vinifera) they were able to more tightly control how the vines grow. This saved the wine industry around the world.
There are only several small pockets and one large one, where phylloxera hasn't invaded. The big one is Washington State in the Northwest corner of the United States. This is where I live. Because of the unique soils (very sandy) and climate (basically a desert) they can grow "own rooted" vines. So, if you are in a place where you can buy a Washington State wine, you are tasting the last place on earth where European vines are grown on their own roots.
Can you taste a difference? I would say not really. There are so many factors that come into play when making a wine. Any subtle influences the own rooted vs. rootstock play in flavor is masked by things like oak, climate, yeast and so on. Just be happy there is a place in the world that phylloxera has not invaded!
