Hrm. I used to not understand what state machines were (I don't have a CS degree) and mistakenly think they were adding complexity. I use them regularly now. I make my own, so they don't have default transitions to remove (beyond throwing 'not implemented' errors when I haven't built a particular transition yet), and I'd still say they're less complex than managing state without them.

Thinking about 'remove default transitions' - are you talking about using a particular state machine library? My default model is writing them. It's kind of like using a feature flag library when a hashtable with features for keys and boolean values will do. OK maybe use a library if the library adds realtime control etc, but not for the basic concept of flags - likewise a state variable and a single transition function work very well for state machines.