It is just a thought. As we have a star to mark favorite a good question, can we similarly have a star to each answer so that a good answer can be marked as favorites by users. That way one can know which answer gave the most accurate and lucid explanation. What do you think?
The proposal seems to be based on a misunderstanding of the feature. The purpose of favorites is not so much 'to mark favorite a good question.' The purpose is to be able to follow and to relocate a question-thread. A more transparent name for "favorite" might be "follow" or "bookmark."
Now, there might be a correlation between good quality and the number users wishing to follow the development, and there are badges for being favorite, but still giving credit or highlighting excellence this is not the point of the feature to begin with. To wit, there is no direct way to sort question by number of favorites.
A tool to highlight 'the most accurate and lucid explanation' exists: upvote.
Moreover "favorite" is in any case a feature that applies more to the question-thread than the question-post, for example new answers activate the "favorite."
One could still entertain the idea to have favorite for answer posts, too. Yet what for exactly? It may be possible one is interested in updates on one answer to a question and note updates to the question or new answers, but really it should be quite rare. What else? If they are extended verbatim it would then allow to be notified of comments on an answer post, which is now not the case. But if one wants this, I would rather propose to modify "favorite" so that it gets activated by comments on answers too.
To sum this up: The proposal seems to be based on a misunderstanding. The potential actual use-cases seem not very significant. I do not see a need for this and believe it would make the user-interface more busy for not enough in return.