Why isn't the coldest serving temperature best for every beer?

Answer: Low temperature slows the release of aroma compounds

Low temperature slows the release of aroma compounds ✓ — Very cold serving temperatures can hide aromas that distinguish beer styles. Cold slows the release of volatile aroma compounds, so fewer reach your nose. The best serving temperature depends on the style and the drinker's preferences, rather than one coldest setting for all beers.

Low temperature drives dissolved gas out faster — Cold generally keeps more carbon dioxide dissolved rather than driving it out faster. Opening and pouring can release bubbles, but chilling itself does not explain weaker aroma by faster gas loss.

Low temperature permanently removes the alcohol — Chilling does not permanently remove a beer's alcohol. Its aroma can become less noticeable because volatile compounds escape less readily, not because refrigeration turns it into a nonalcoholic drink.