Most wines that you can buy in your local supermarket or off license are mass produced using mainstream methods of growing grapes (viticulture) and winemaking (vinification). This section of the wine business is about making lots of wine as efficiently as possible as buyers will want to buy as cheaply as possible. This means using chemicals that result in wines that taste expressionless and indifferent.
Natural Wines are made from smaller independent producers who genuinely care about the wines they make. They are the opposite of mainstream winemakers and focus on quality and not quantity.