That is incorrect. There are two very important reasons that all ballots are counted. 1) down ballot races 2) parties (Libertarian, e.g.) wanting to have candidates on the ballot in subsequent years must have a good enough showing in the current election.
A state can be declared for a candidate without all ballots being counted if the number of absentee ballots remaining to be counted could not reverse the outcome. But eventually, they will all be counted.
Thanks.