I was always under the impression that what people mean by metaphorical is that they aren't actually entities, more like tools. Like, climbing yourself up the ladder with steps that don't exist but acts as if they do. Maybe I've been talking to too many Discordians...
That's a possibility. An observation, if you will.
In Paganisms of antiquity, gods were understood as categorically distinct from humans. They're fundamentally greater than humans, and as greater powers, they were worthy of worship in a religious context. Offerings were given to the gods out of respect and reverence, and sacrifices might be made in their name to petition for their blessings.
In the modern day, Pagan gods might be approached differently. Instead of regarding the gods with the dignity and respect our ancestors gave them, there are some who will plug-and-play them like tools into spellwork for their own ends. Essentially, they use them as symbols, or what you might be calling metaphors. These people may not identify as polytheists or contemporary Pagans; they're New Agers, occultists, or some other sister movement that happens to use Pagan gods for their window dressing. They don't really worship the gods, in many respects don't really believe in the gods, and are perfectly comfortable regarding them as mere symbols/metaphors because that's what they function as in their path.
The idea of using the gods as tools/symbols is controversial within the Neopagan community. I don't think we need to get into that here, but what I want to emphasize here is the observation that we shoudl be cautious in labeling people who "use" the gods - and who tend to take the "they're just symbols" approach - as necessarily polytheists or Pagans. What they're doing isn't an act of worship, they're desacrilizing the subject, and in at least some cases, they genuinely don't identify as polytheists (or even theists).
