As a Roblox developer, it is currently hard (without wasting Robux) for a developer to set up a VIP server.
For example, if VIP servers are enabled on your own game for R$200, the owner of that game would have to pay that amount to enable it and then due to the taxes, only receive R$140 (Builders club) or R$60 (Non builders club) back from their purchase.
This is already a feature of gamepasses, where the developer who made the gamepass owns it upon creation and can therefor use it’s perks in-game.
It makes sense for a developer or a development team to have a private server that they can use for testing outside of studio, without wasting Robux.