I guess they mean the freedom (or lack thereof) of the software license that comes with your OS, ie. 'you should be able to hit the software with a metaphorical hammer', which technically isn't possible with the Windows 10 license.
For example, for $4k, you can get this with specs roughly equivalent to a normal developer machine: https://www.raptorcs.com/content/BK1SD1/intro.html
[0] https://www.winehq.org/pipermail/wine-devel/2019-February/14...
I bought two of these last year and they're great, stuff your own memory in there, add some storage and off you go.
Edit: clarified that this would be a mainboard + CPU.