I mean, they're clearly not magic in the sense of making any particular individual invulnerable, and they won't prevent community outbreaks of Omicron.
But in terms of masking reducing individual risk and potentially community prevalence, they're as applicable as they've ever been (that is, more so if the masks are higher quality and well fitting, less so if they're not). Which is particularly critical for, e.g. critically vulnerable individuals during potential exposure that they can't otherwise avoid (e.g. if a critically vulnerable person has to take public transport to a hospital and back, they'll be at lower risk if they and other people are wearing masks during that journey and at the hospital than if they're not).