What you posted is partially true – depending on what you actually mean by that.
1) If you mean that some of the quotes you find online have not been quoted by the person who they are attributed to (as in your case Abraham Lincoln), I have to agree.
2) If you mean that they are not true as in the real meaning of the word, some are, some are not
3) If you mean something else, please enlighten me
4) If you just wanted to add your tuppence worth, then be it