It originally started out as something from NTInternals. They were building small utils with capabilities similar to what they had become used to in their Unix background. Then they focused on all the low level tools which led to MS buying them.

Not having an installer is actually a bonus. Far too many "simple" Windows programs seem to need Gigabytes of DLLs installing to Windows folder and spray themselves all over the system. /Windows bloats massively after a couple of years of active use. An exe I can keep in a folder, or drop into the path and simply delete if no longer useful.