Not at all. The Japanese use minimal kanji daily and even less than this number in writing. At the same time, they read it just fine. A kanji is simply a form of writing that uses pictographs to make a word distinct from other words to show its meaning for the reader. It was brought over from China and used in Japanese writing since then. The Japanese language is written with kana most of the time, but when they need to use kanji, they instead use the form of mixed kana and kanji than pure kanji.