alt Hacker NewsThe engine doesn't understand natural English. It only understands the hard-coded words. The game author forgets to include some common verb or an uncommon spelling, and oops, an otherwise great puzzle is now very frustrating.
There's a reason "Guess the verb" meme exists. There's even a satire game on this concept: https://ifdb.org/viewgame?id=35arqepm2q92hcqu
The engine is the ZMachine, and depending on the target and the grammar (IF6+English, or better, i7) the 'guess the verb' issue straightly died in the 90's.
Your comment coudn't be more outdated since the Curses! release for the ZMachine in 1993.
The v5 machine release was much better than the v3 one, and the v5-V8 ones allowed semi-complex phrases with indirect object pronouns after a previous entered phrase and much more.
Go play Anchorhead and compare it to a z3 machine game from Infocom, or any game made it with Puny Inform.