Keep in mind that questions regarding certain topics that are common to all stack exchange websites are probably better suited for Meta Stack Exchange than English Language and Usage's meta website and this especially pertains to the software restrictions. This question has been answered there by Shog9. It is meant to prevent mass deletion by frustrated users, which would cause the loss of many possibly useful answers.
Do remember that Stack Exchange does not consider our posts to be our sole property, but rather a valuable communal possession. Aside from requiring everything we post to be subject to a CC-BY-SA 3.0 license as indicated on the bottom of every page, users may not delete accepted answers and anything we post and later delete is subject to be undeleted by users with access to moderator tools, which aside from the formally elected moderators, also applies to a lesser extent to people like yourself with ten thousand or more reputation points. If a whole bunch of these disappeared, it would take quite a bit of effort to track down the good posts and make them publicly viewable to people who may benefit from them again.
Reducing the number of questions a user may delete to a reasonable number probably makes it easier to spot problematic deletion and reverse the damage before it becomes too bad. Five may not seem like very many to long time users, but we also have newer users with fewer posts to consider and it seems to me like it is usually more than enough if you are only noticing this now, as Shog9's answer is over a year old.