That is totally correct, but the vineyard's business model will determine whether they are going for high quality or quantity. Some will have multiple labels so that they can cater to different price points.

Resistant means that American rootstock tolerate phylloxera feeding on them. It does not mean that phylloxera can't or won't feed on them.

As far as I am aware, grape phylloxera only feed on roots from the Vitis genera of plants (grapes). America has multiple species of native grapes, nearly all of which are resistant to phylloxera damage. Since they evolved together, phylloxera and American grapes coexist without too much trouble. The problem started when American grapes were brought to Europe, with phylloxera still on their roots. Vitis vinifera, the wine grape, is the only grape species native to Europe. It had no resistance to phylloxera. Any wine grape infested with it will slowly die. The solution was to graft wine grapes onto American rootstock. This became standard practice in nearly every wine growing region worldwide.

Now I said nearly. There are some wine growing areas that have very sandy soils. Phylloxera prefers clay soils and does not do well in sand. Some of these areas have very limited populations of phylloxera. Washington state in the United States is one example of this. Many vineyards there have self rooted vines. In the few places there that have a phylloxera infestation, the standard practice is to replace any failing vines with grafted vines. Phylloxera spreads very slowly when it's not being transported by humans, so that is not a large number of grape vines annually. Grape vines do also have a production lifespan (production does start to drop off after a few decades), so any areas with more loamy or clay soils in Washington are considering replacing with grafted vines when they do, just to forestall any problems. Areas with sandy soil probably won't bother.