I wanted to answer to 2 questions and it looks that my answer to the second question is not accepted because I answered the first one less than 3 minutes ago... why is there such a restriction? What is the motivation behind this?
The rationale behind this is explained here by one of the Community Managers:
What kind of answers are you posting, if they take less than 3 minutes to write? Take an extra minute or two to provide a link to your sources, or fix spelling.
(As others note, the limit exists to reduce the damage abusive users can - and, prior to the limit did - cause the site)
The good news is that you now have more than 125 reputation, so you're not affected by this anymore.