Its an interesting question.
For a person who has been browsing for some amount of time and is used to such a system would essentially do what you would, open in a new tab.
However there is a big percentage of people around who wouldn't be opening it in a new tab. They would simply click on the result, see it and then come back to the list and browse through other results. For example, my dad would always click on the link and NOT open in a new tab. He would even click on the back button to go back to the previous page! (and not the backspace button which is more convenient for moving back).
So yes, there are people out there who do not open in a new tab, however in my opinion, the favorites button is NOT a replacement/alternative to that.
Let me make myself more clear. If a guy is not using opening a new tab and using the favorites as an alternative method, then for that guy the look up for favorites should even be intuitive enough to figure out where he saved it.
For example, the house list you mentioned. If someone is favoriting the list to save it for future- where does he look it up from when he comes back? Is that intuitive enough for this not so savvy user to figure out? Because if the user was even slightly accustomed to looking through lists of results, he would have realized the benefits of opening in new tabs. So, if he is not that savvy, then you are expecting him to figure out how to look up his saved results from the favorites tab.
So the answer basically is, from the user point of view, its not just if favorites is an alternative/good way to save results; the question is how intuitive it would be for this user to come back and look up results.