The hard part in the early spellcheckers wasn't figuring out that you want to find a set of words with a minimum edit distance from the input.
The hard part was fitting the dictionary in memory, and then searching all possible strings 1 and 2 edits away from the input to find the candidates.
The progress is that we don't have to care about storing 2.5MBytes (they ran on machines with 640k!) in RAM, or searching it 100,000 times (e.g. edits2('something')).
