Sometimes, if a daily puzzle continues all the way to checkmate, there will be multiple "correct" moves (this is called a "cook," and is not allowed in accurate puzzles) at the end, so they cut the sequence short in order to keep the solution unique. It's assumed that if you make the correct moves, you would easily know how to play the ending.
Daily puzzles

yes, but one guy showed the answer to a problem, I was two moves short.
I'm not sure what you mean by "two moves short."

So a mate in 2 was left hanging...was there more than one way to do it, or would the correct moves have been forced? I'd like to see the actual puzzle.

Aha! After 2. Re8+ Rf8, White could checkmate with either 3.Rxf8# or 3.Qxf8#. One of these options would have to be "incorrect," and as I said before, that's a cooked solution.

That's because after 1.Nxf6+ Rxf6 2.Re8+, you HAVE solved the problem. That's a combination where there are no other moves that work, but the puzzle ends there to prevent any alternates (there would be two possible checkmates after 2...Rf8). It's understood, though, that White has an easy mate next move, so the puzzle is "solved." Does that answer your question?

The people you say did the last two moves simply inserted a chess diagram and move sequence into their comments using Game Editor. In additon to the puzzle moves, they added the last two moves just to show White really had a forced win. You could have done the same thing if you'd posted a comment in that thread, but in the OP no further moves are allowed after Re8+.
Whenever I do a daily puzzle, it never ends with a checkmate when it is suposed to.