<p>IMO this is because long questions take longer to read, which exhausts the attention before the main matter is stated.<br>
A good lengthy SE question is also possible, but it should follow </p>

<blockquote>
  <p>question ~> details ~> more details </p>
</blockquote>

<p>scheme rather than </p>

<blockquote>
  <p>details ~>  previous results ~> more details ~> version of software ~> self-assessment of desperation ~> ... ~> question*.</p>
</blockquote>

<p><sup><sub>(*) Nothing personal, general inspiration.</sup></sub></p>
