I was trying to help someone out earlier and I needed more information on the issue at hand. When I clicked on add a comment I was alerted that I need a minimum of 50reps to add a comment. I do not have that amount of reps so i decided to answer the question in order to remedy the issue the user was having. After doing so I was down voted. I was wondering why this rule exist? I could have potentially answered the question but was not able too.
Comments are temporary "Post-It" notes left on a question or answer. They can be up-voted (but not down-voted) and flagged, but do not generate reputation. There's no revision history, and when they are deleted they're gone for good.
Please note that you can always comment on your own posts, and any part of your questions. However, commenting on other people's posts is a privilege.
There are numerous privileges granted to people at levels lower than 50 reputation, and this is usually an anti-spam/harassment measure. I know it can be frustrating when you need clarification and you're brand new to the site, but the answers section is purely for answers.
A single downvote can easily be remedied with a well written answer though, and reaching 100 reputation shouldn't take you long, the maximum reputation earnt per day is ~300 and some users regularly reach that on a daily basis
Note that if you have 100 or more reputation on any Stack Exchange site, you're granted the trusted user privilege and immediately earn 100 reputation on any site you log in to