What is the benefit of “keeping wine on the dregs”?

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Dear Dr. Vinny,
What is the benefit of “keeping wine on the dregs”?
—Don, San Juan Capistrano, Calif.
Dear Don,
In the usage you’re referring to, the “dregs” is a reference to the lees, which are the solids that precipitate out of fermenting wine, namely spent (dead) yeast cells, bits of grape skins seeds and pulp, tartrates and some other phenolic compounds. Either way, it doesn’t sound particularly appealing.
But those dregs, or lees, can impart additional flavor and body to a wine, especially the longer the wine and lees remain in contact (also known as sur lie aging). Intermittently stirring those lees up, a process called bâtonnage, is favored by winemakers looking to bolster a wine’s richness and aroma complexity.
Eventually the winemaker will separate the wine from the lees, usually via a process called racking, or transferring the wine from one barrel or tank to another and leaving the settled lees behind. Usually (but not always) the wine will also be filtered and/or fined to improve clarity and remove any remaining solids.
—Dr. Vinny