Another way to think of this is not making a “game engine” but just “making a game”. Get rid of all the generic stuff and use some common patterns that fit the game exactly. No need to over-abstract!
That’s not what the person you replied to is saying though… They’re saying just use an existing engine, and if you really need to, you can always write your own engine later if you really need it.
I read it to mean the other way around: If writing the engine interests you, do it, you can switch to another existing game engine later, and your experience is not lost.