“Several of these protocols are standards” My understanding is that even if the protocols look standard, Cisco made some modifications on them : VXLAN (fiels to transport ACI Policies), ISIS (added the multidestination tree) and hence are note standard anymore.
“Does it require proprietary server ?” Not prorietary servers but proprietary switches…So you are locked in regarding the software and the hardware. Both can’t be decoupled. If you choose to move to another switch vendor, you need to change the hardware and sart learning new software and protocols skills.