I think you would struggle to NOT build a more performant PC for the same price.
https://pcpartpicker.com/list/brbFsK This is $50 more but it has 1TB of storage and a newer generation of both CPU and GPU and will absolutely destroy it.
I'm sure you could get actually easily cheaper and better even, I haven't followed the market a lot lately.
Prebuilt are likely to be even better deals because they will use some cheap noname parts for the RAM and the PSU, which is mostly fine.
Even with similar specs you can still get more performance from a PC because Valve is throttling the Machine to keep thermals down.
For me, size and aesthetics play a role. A PC like that is huge and, imo, much uglier. I know a lot of people do not care but I am sure I am also no the only one.