Lars Carlberg wrote: Many of these "entry-level" Rieslings, even if from purchased grapes, come from steep slate slopes and old vines. Moreover, the wines have plenty of ripeness nowadays, so that chaptalization is less common than before.
Very true. But to use the designation 'Gutsabfüllung' (filled by the producer) or to even use the term 'Weingut' on the label, cartons, and promotional matierial technically including the company website, the grapes have to come from parcels farmed by the producer - either owned or rented parcels. Many of the contracts for rented parcels last twenty years or more.
Some producers will just print thier name on the lable (like Selbach instead of Weingut Selbach-Oster) to get around this.