They were originally created for do it your self WISP providers. The OS is open sourced.
And it's always evolving. If you had trouble years ago give it a second try now. The current internal RouterOS and SwOS webGUI's are a lot easier to use than the command line or WinBox and there's even a Quickconfig pane at the top that will get you running in a way that can handle 90% of usage needs.
Once set they are very robust and the router models with built-in wireless seem to do well with range and crowded WiFi environments.
Yes I still need to Temviewer to my IT gurus sometimes but it gets less and less needed every time they show me how to do something complex.