More like you’re not familiar enough with the video encoding performance of a typical NAS that is not in the thousand dollar range. Or what’s a NAS — it can be anything really.
There’s a pretty well understood concept of what a NAS is; this isn’t a complicated philosophical problem.
A very common workflow in motion picture production is to use NAS for storage on a fast network, mount the SMB share, have a script/tool/app that monitors the ingest directory and writes to an output dir.
FWIW the key differentiator between a NAS and other types of network storage is the protocols they use.
If files is the main primitive, it’s a NAS; it’s its blocks it’s considered a SAN.
Sometimes SANs have NAS “heads” for clients that want file access or a block level storage device.
It would be helpful to understand your specific use cases in more detail, particularly for batch transcoding (my understanding is that this solution is not about stream transcoding).