Some interesting stuff here--I wanted to add a couple of ps's.
True enough one tends to be true to one's source, whether written lyrics or recording. That's why it's great that different variants are available. On the DT or elsewhere. Anyone who has any version of Child's "English & Scottish Popular Ballads" knows that you can't just "learn" a song out of it--most songs have multiple variants, up to 30 in some cases, and there are no tunes given. And usually no single variant is quite satisfactory to me--a redundant verse here, one that makes no sense there, and so on.
Best case is to have more than one recording, more than one text, then if it still doesn't work for you--add your own variance!
But beginners often need more certainty. Most have trouble distinguishing between a variant and a mistake, (Don't we all) and are baffled by suggestions that there's more than one "right" way to play something. Handle gently.
Here's my modest suggestion for ameliorating (my Big Word of the Month) the number of overeager requests for info thats in the DT: it would do no harm to add a couple of explanatory lines to the search engine window up top there. ("To find a song lyric: Type full or partial song title, or lyric fragment, and press 'search'") Since it's evident that many newcomers are just as new to net lingo as to folk process, I bet that would help a lot.
Bill