Quoting is just a means to an end and should be used parsimoniously. Quotes should be used to back what you say or to illustrate a particular point. What is nice about this site, as well as forums and mailing lists in general is the personal touch. Users are writing a text and put in their experience, their understanding of a situation etc. and use their words. To suck off data from A to spit it back at B, we don't need humans. Computers are better at this.
I think that the same is true for pictures.
You are right when you say that quoting allows to "preserve" information in case the original sources goes down. But this is outweighed by the fact that the original source may be corrected, updated or improved. That leaves us with an inaccurate piece of information.
A case where quoting makes a lot of sense is when you quote from a source that is not available online or at least not to everybody. But even then it has to be used parsimoniously. Don't abuse.
Regarding the precise case here, I don't think that the answer is great. I am surprised to see it got a score of 13 (and now 12). What's so great about copy-pasting? An answer of a user who provides personal first-hand experience only got 6 (and now 7) votes. That's a bit weird. This being said, the question is debatable too. It is either too broad and opinion based. Not the kind of question welcome here.
If quoting is excessive, the users have the possibility to issue a negative vote. And the moderators can interact too. If there is no real original or personal contribution they could remove the answer and put the link into a comment, provided the source is available online.