Hmm… Gordon Freemann having no lines was much more jarring that the silent protagonist in the Portal series.

Gordon is supposedly a brilliant scientist, but gets ordered around by NPCs that do nothing.

Portal protagonist has likely brain damage from being in stasis for a while, so I can assume they are just mute.

So it really depends on the game, setting and story, if a silent protagonist works or not. But having some character with emotions and agency would be good anyway, without requiring them to speak.