Why is there a huge amount of old questions migrated from Super User? Is there any interesting story behind it?
Searching on questions sorted by "newest", and going to the last page of results (oldest questions) I found at least 30-40 consecutive (according to time) questions migrated from the Super User.
Examples:
I suspect anyway, that it is a natural result of this site being opened.
Consider:
What's probably happened is that there was a lot of pent-up demand and, once this site opened, Super User finally had a place to send decent but off-topic questions.
After seeing a couple of your examples, it's clear. Those questions pre-date the creation of Web Apps. So...
Since the meta data of a question, like the date/time it was created, don't change in a migration, if you sort strictly by age many of those questions will be from before Web Apps existed to accept questions of its own. (The private beta of Web Apps began June 30, 2010. By definition any question with a date before that will have been migrated from elsewhere.) The same will be true of many of the early Area 51 sites. (Lately, however, the policy has been not to migrate questions to sites that are in beta, so you won't see it as much or at all at other Stack Exchange sites.)
1 A considerable motivation for creating Web Apps.
The first site was Stack Overflow, created in 2008. In 2009 were created Server Fault for system adminsitrators and Super User for computer power users. The last use was promoted as "anything goes there". Other sites were created known as Stack Exchange 1.0. Later was decided create a site to manage site proposals which was called Area 51. Sites derived from this process were called Stack Exchange 2.0. The first one was Web Applications.
Apparently most of the poeple participating in the Web Applications proposals were Super User users. Somehow many old questions from Super User were migrated but later to other sites but later the migration policy was changed.
Many of the questions that were migrated looks to be "broken windows":
innapropiate questions to justify posting similar questions.
The "broken windows" might still be open because there is not in place a exhaustive review process. They are revised case by case as the questions are bumped due to being edited, a new answer be posted or were brought to mod attention directly, i.e. by a flag or indirectly, i.e. by link in or search results.
