hadrianjeffs
It's not quite right that the online site "rejects every answer until you enter the right one". What happens is that you submit the completed puzzle and if there are any incorrect answers they are highlighted and you have the option to continue with the submission - rather pointless! - or return to the crossword. You could, if so inclined, submit it with each possible answer until you get one accepted, but this is rather unnecessary as you can have up to 5 letter hints.
I hope this explains why some of us are able to give a definitive answer to some crosswords, but, as Rollo has said, this does not apply to the Saturday (and Monday) General Knowkedge crosswords.
I am sure that there were debatable answers before the site went online, it's just that by the time the solution was published most people had forgotten about them.