Ugh, can we taboo "smarter" please. Are we just playing with status markers? Can't we just go do awesome things instead? If people start faking that, well "mission fucking accomplished," as xkcd put it.
Much of concern with IQ seems to be about status, or more generally is purely about evaluating people without a stated purpose of the evaluation. Is your suggestion to just evaluate people based on awesome accomplishments just your way of playing along with this game, trying to divert status from IQ to accomplishments? If not, the usefulness of your proposal likely depends a lot on the purpose for which we're ranking people: if you want to predict future performance in domain X, then past performance in domain X might well be superior to IQ; but to predict future performance in a different domain Y, IQ is probably still the best bet.
I've never heard of anyone saying "I thought that person was really intelligent, but they turned out not to be", and when there are scandals about people with fake credentials, they don't seem to come from people with fake credentials making mistakes-- instead, someone checks the history.
It seems to me that you can find out a lot about people's intelligence by talking with them a little, though I've underestimated people who were bright enough but didn't present as intellectual.
The real problems are with identifying conscientiousness, benevolence, and loyalty-- that's where the unpleasant surprises show up.