A plot hole is “that plot point literally could not happen given the established rules of the universe. It is impossible.”
That's a bit stringent isn't it? I mean, it is not physically impossible (by the known laws of physics of a given 'verse) for a lot of things to happen which don't make any sense. There are lots of rungs on the possibility ladder, right?
Logically Possible (does not entail self-contradiction)
Physically Possible (does not violate natural law)
Biologically Possible (does not exceed architecture of an organism)
Sociologically Possible (does not contradict what is true of people, in general)
Psychologically Possible (does not contradict the inner life of the character)
We might, for example, establish Richard Kimble, a man desperate to clear his name and to catch his wife's killer. We might watch years of Kimble attempting to do so. If we saw an episode where it would have been relatively easy for Richard to clear his name and to catch the one-armed man, audiences would protest that this was a plot-hole.
Why didn't he just call Lt. Gerard and tell him that the one-armed man was trapped in the gatehouse and that the exculpatory evidence was right outside the gatehouse? This does not violate logical law, physical law, biological law, or perhaps even what is sociological possible, but if it violates what we know about the character (especially in relation to the point of the artwork), then I think people would be right to object that this is a plot hole.
I think you're right that a plot hole is not,
"I have a better idea," but that you are too restrictive in limiting it to physical possibility. I think it would be closer to it to say that competent audiences would say of a plot hole that,
"That would not/should not have happened." It just has to be good enough that even if it isn't the best idea, that it is the sort of thing you would expect to see in this (fictional) world, given your knowledge of the real world, general narrative rules, medium specific expectations (e.g., it is not confusing to us to watch a film with "cuts" and "wipes" and other conventions).