[adrian_b]

The use of grafting for grapevines has become necessary only after the insect phylloxera has been brought accidentally from USA to Britain and France at the beginning of the second half of the 19th century and then it has devastated most European vineyards.

The American vines are resistant to phylloxera.

Previously, grapevine was one of the few sources of sweet fruits which did not require grafting, because it propagates naturally through clones.

[CSMastermind]

It's worth noting that there are a handful (like less than 10) vineyards in Europe have escaped infestation so far and thus have their original rootstock:

https://www.decanter.com/features/phylloxera-the-great-escap...

This includes 2 Pinot Noirs in France, 1 Tinta Barroca used to make Port in Portugal, 1 Sangiovese from Italy, 1 Monastrell from Spain, and 4 Nerello Mascalese from Sicily.

There used to be 3 Pinot Noirs in France but one succumbed in 2004 and the Monastrell in Spain is verging on succumbing.

There are also vineyards that have been planted with European rootstock since the infestination of the continent. These include vineyards in Portugal, Sicily, California, Chile, and Australia where soil conditions prevent the bugs from getting to the roots.