Why do breweries use brite tanks?



Why can't they just pressurize the fermenter after fermentation is done to carbonate the beer and then fill bottles/kegs directly from the fermenter?

After an initial or primary fermentation, beer is conditioned, matured or aged,in one of several ways, which can take from 2 to 4 weeks, several months, or several years, depending on the brewer's intention for the beer. The beer is usually transferred into a second container, so that it is no longer exposed to the dead yeast and other debris (also known as "trub") that have settled to the bottom of the primary fermenter. This prevents the formation of unwanted flavours and harmful compounds such as acetylaldehydes.

I beleive also the brite tank was a less complicated vessel so likely cheaper than the fermentor. By adding a brite tank for conditioning, it freed up the fermentor for another batch of beer without having to invest in additional fermentors.

Since the filtered beer is "bright beer", the receiving tank is a "bright beer tank". Once the beer is in the bright tank, it's carbonated then packaged.
No matter how, using the brite tank is necessary, if you do not want to buy additional brite tank, we also can added the carbonation stone in the fermenter, The fermenter with carbonation stone is available to be used for fermentation and maturation in one vessel (unitank).