I mean yes... but in bare metal there's a lot of things that need to be handled:

- Network topology management, IP address management (IPAM) and host associations (DNS, DHCP services or Static IP assignment)

- IPMI to power on/off machine and change boot orders, serial consoles

- Disk configuration (MD raid sets, LVM configuration, partitioning)

- Firmware of all the components

- Burn-in testing

- Passing configuration to the host OS for application/OS configuration

- Detecting hardware failures and tracking response.

- Install the OS

MaaS does most of these things, but it's all the life of bare metal. So "just a tool to install a chosen OS" undersells the complexity in this space.