I get variations of this question all the time. I also get questions about backing up in general where folks are backing up to DVDs.
This is also one of those questions where the answer has changed over time. What was once a reasonable and common practice is now something that at best is impractical, and at worst a disaster waiting to happen.
The short answer: heck no! You should not back up to DVDs.
The longer answer has several reasons behind it.