I would say it depends on what projects you pick up (and whether you do it selectively). Your voice (from an objective viewpoint) will be dictated by the projects you take, just like the soundtrack you create is dictated by the project. Comparison to pure music/sound is just not valid, because there you can be anything you want, which effectively means that one really defines the voice of oneself just like a band defines its voice. And to draw an analogy, in pure music/sound you define the sound as well as the imagery/impression it creates. Plus music is not as strictly position- and style-fixed as voice and SFX most of the time are.
Would you say that certain SFX recordists/producers have their own voice or is it just the libraries that they tend to produce? Would you say that sound artists working on film soundtracks have a certain voice or are they just picking projects that fit to their own interests or their previous work. Or would you ever consider that it's the voice of the sound artists that we hear, rather than the voice of the project/piece?
Could it be that, in fact, given different people the task of producing a soundtrack for the same media piece, the results would have corresponding elements and the voice and the differences could be explained by what sounds and sound sources they happen to have access to, not largely by their editing style? And as a second notion, would it be possible that "the voice" is not actually the sound itself, but what sound and where? Public sound design competitions are interesting "group studies" for this reason, because I feel that they are a good way to hear how the work of some people happens to be reminiscent of others, whereas some seem to really stand out (which arguably is possibly a completely subjective perception).