I just came across this:
Different strains of Saccharomyces cerevisiae produce different proportions of carbon dioxide and alcohol. Baker's yeast is a blend of several strains of Saccharomyces cerevisiae chosen for their flavor and ability to make carbon dioxide, which causes bread to rise. Brewer's yeast is made of strains chosen for their alcohol-producing ability and tends to have a bitter flavor. Brewer's yeast is considered an inactive yeast while baker's yeast is an active yeast. In an active yeast the yeast cells are still alive, whereas they are killed in the process of making inactive yeasts, like brewer's yeast.
Which I found surprising, thinking yeast was useless (for anything) if not alive, and having read of rehydrating and proofing with malt extract and checking for signs of life, for example:
If it's not showing signs of life (churning, foaming) after a half hour, your yeast may be too old or dead. Unfortunately, this can be a common problem with dry yeast packets, [...] Have a third packet available as back-up.
Is the first article just plain wrong (certainly it seems much less of an authority on brewing) - or is there some subtlety here that makes both quotes sort of correct but not quite telling all?