Selfhosted

People are using NAS for things they aren't meant to do. They are a storage service and aren't supposed to be anything else. In a typical data center model, NAS servers are intermediate storage. Meant for fast data transfers, massive storage capabilities and redundant disk fault tolerance. We are talking hundreds of hard drives and hundred gigabit connection speeds inside the data center. This is expensive to run, so they are also very energy efficient, meant to keep the least amount of required disks spinning at any given moment.

They are not for video rendering, data wrangling, calculations or hosting dozens of docker containers. That's what servers are for.

Servers have the processing power and host the actual services. They then request data from a NAS as needed. For example, a web service with tons of images and video will only have the site logic and UI images on the server itself. The content, video and images, will be on the NAS. The server will have a temporary cache where it will copy the most frequently accessed content and new content on demand. Any format conversion, video encoding, etc. Will be done by the server, not the NAS.

Now, on self-hosting of course, anything goes and they are just computers at the end of the day. But if a machine was purpose made for being a NAS server, it won't have the most powerful processor, and that's by design. They will have, however, an insane amount of sata, PCI-e channels and drive bays. And a ton of sophisticated hardware for data redundancy, hotswap capacity and high speed networks that is less frequent in servers.