One key motivation for building this was that, despite there being other similar tools out there, I wanted a utility that was language-agnostic, meaning I could

One key motivation for building this was that, despite there being other similar tools out there, I wanted a utility that was language-agnostic, meaning I could make test assertions without having to write in some particular language. So Mock was designed this way where assertions are made by simply doing HTTP calls. Another point was installation - setting up Mock in your CI is a matter of just downloading the executable file, where other alternatives required me to install Java SDK, or Nodejs, or whathever programming language their utility was written in, resulting in CI scripts more complicated than what I wanted.