FireDac calls it Aggregates Fields. Aggregates define the client-side aggregating formulas, which are automatically maintained and calculated for a group of records or for all the records in the dataset. All the records in the group of records have the same field values for the defined set of fields. The Aggregates property computes for groups of records that are associated with one of the indexes. These aggregate expressions will be calculated only if the associated index is current and active.

Agree. There are many times when one needs a field independent of the underlying database.
Using calculated fields is problematic if one needs to recursively change the calculated field to update the existing DB field.
e.g. suppose one had a table with a 'primary' field used to calculated other field values such as a '%' field that is used to calculate the quantity in grams based on some 'total quantity' factor. If the 'grams' field is 'auto calculated' then one cannot change this field value and re-calculate the '%' field.
As Piotr has commented, many of your opposition companies have this ability in their DB components so they feel it's necessary too.