On Do "list of something and why" questions belong to SO? two of the answers (given from Community managers) essentially say that questions requesting a list just for the sake of building a list are not much useful.
First off, those questions are not constructive: They don't require specific expertise, and they get answers where users express their opinion. As such, they quickly become polls, where everybody votes for the list s/he likes better.
They are never ended, as there is always an item that can be added to the list (and other items that should be removed). This is what @Grace Note was implying with, "Many of these repositories lack high quality, requiring maintenance that never gets done."
Secondly, when the question is asking for something subjective, and every answer is equally valid, that question is expressly discouraged from the FAQ.
It is true that accepting an answer is something subjective (the OP decides basing purely on personal criteria), but the answers need to be objectively valued from who votes. Experts should be able to vote basing on their expertise, and understanding if a site is an example of mobile site doesn't require any specific Drupal expertise.
Even adding context to the list of mobile sites, the list would still be subjective: Every user has her/his own list, and a user's list is different from the one made from another user.
I think it would be preferable to have a more straight question. I suppose the reason for asking examples of mobile sites is understanding how such sites could be built; if that is the case, asking which modules can be used to build a mobile site would be a better question, provided that the question is enough detailed about the requirements.
It is similar to questions about tutorials: Instead of asking for tutorials, the question should ask how to achieve something. Often, the questions asking for a tutorial make the assumption they exactly need that feature, when it would be better to use another feature, or another approach.
I would add a note for those questions that seem to ask for a list, but that give enough restrictions to what it is acceptable, making the list contain few items (from 2 to 5). This is what happens, for example, when a question asks to list all the modules with specific features, and those features are enough restrictive.
In this case, it is probably better to remove any reference to a list of modules, and let the users answer suggesting any module they know. At the end, the OP just needs to know which module should be using, and which of the existing ones better suit her/his requirements. (Nobody is going to install two modules with the same purpose.)
