our datamover works in the same exact way on Windows and Linux. Having the possibility to choose a preferred platform is something that gives our many customers to use what they prefer.
One "why" for using linux repos however is when the final storage is an NFS share: since proxies cannot write directly to smb, you need a gateway server. Linux can mount an nfs share via fstab as a regular mount point, on windows nfs can only be mounted in userland, thus is cannot be used by our datamover that runs as system.
Other than that, as said, is a matter of preferences (and some scenarios like a failover cluster where I personally prefer linux servers, but again is MY personal taste, not a suggestion as Veeam employee)
EMEA Cloud Architect @ Veeam Software
Veeam VMCE #1