It is not impossible. In fact,throughout the series, some shinobi have been mentioned to have achieved similar feats: 1. * Minato was able to defeat an entire Iwagakure army with minor assistance 2. * The Third Raikage also fought 10000 shinobi alone for 3 days and nights. Likewise, there are those that can stand up to tailed beasts which isn't an easy/normal feat to achieve. It's not an impossible feat, it's just a matter of how skilled the shinobi is and how skilled their opponents are.