There's a perfectly good structural reason for having chainstay and seatstay bridges apart from needing to have something to hang a mudguard off.
It's less to do with that more to do with the gigantic gaps between the bridge and tyres.
In the photos it's fitted with 650b tyres. I assume the clearance is for use with large 700c tyres.
@Brommers started
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It's less to do with that more to do with the gigantic gaps between the bridge and tyres.