Are you sure? If anything, spelling along makes it hard to read Chinese or Japanese. Examples: can Japanese people correctly understand this: “かんじをせんねんいじょうつかっていたけいいからかんじをはいしするとぶんしょうによるいしのそつうにへいがいがしょうじるからです”？ In fact, the following two different sentences both have the same above kana：
「監事を専念異常浸かっていた敬意から監事を配しする飛ぶん商による石の疎通に兵が意を招
じる空です。」
「漢字を千年以上使っていた経緯から漢字を廃止すると文章による意思の疎通に弊害が生じる
からです。
Or how about くさくさくさくらくらくさくさくさくさくさくさくらさくさんさくさんくさくさくらんくらくら？
Or how about こうないしゃせい？Is it 校内写生 or 口内射精?
In all seriousness, even Koreans still debate whether they should continue to use some Chinese characters, and they do so in poems and literatures. For instance, 악유원 means shit, yet 乐游原 has layers of meanings. Chinese and Japanese have too many homephones to use a spelling system like Korean. Unlike Chinese, where individual characters correspond closely to morphemes and carry distinct meanings, Japanese is organized around words as the fundamental linguistic units. Furthermore, because Japanese employs a pitch-accent system rather than the kind of lexical tones found in Chinese, writing some native Japanese words (和語) entirely in kana typically does not create confusion.
Also, Japan had at least three major attempts to remove Kanji. First time: The Tale of Genji, the world’s first novel, was written by a woman entirely in kana, with only a small number of Buddhist terms in kanji—terms which, in theory, could also have been rendered in katakana. This demonstrated that early Japanese could be expressed systematically and fully without using any Chinese characters at all. Nevertheless, the Japanese chose to retain kanji.
Second time: During the Meiji Restoration, slogans such as “Abolish kanji, or East Asia will never grow strong” were popular. In the end, Japan found that it could modernize, prosper, and even become one of the five permanent members of the League of Nations while still keeping kanji. The decision was made to continue using them.
Third time: After World War II, General MacArthur commissioned a team of American education specialists to work with Japanese experts to discuss whether to abolish kanji entirely, and to consider the possibility of fully romanizing the Japanese language. Yet, they decided to keep Japanese.