Earlier quoted context omitted.
Not for beginners. But for fluent speakers, kanji are very necessary to distinguish all the homophones. E.g. 効果, 硬化, 降下.. are hard to learn, but they're clear. こうか is much easier to learn, but it could mean any of 10-15 unrelated things.
All of which native speakers have no trouble distinguishing between in conversation when there are no Kanji anywhere. It's the same with homophones in any language, usually the context makes it clear because the alternatives don't fit. The homophones in Japanese and Korean pretty much all come from the vocabulary they share with Chinese which makes up the bulk of the vocabulary for both those languages. One doesn't u…
Chinese/Japanese has a level of written mutual intelligibility. Korean lost it.
> Japanese on the other hand I have seen even natives struggle to read.
It's like a native English speaker encountering new vocabulary. Happens quite often.
> Heck even the existence of furigana in novels is an admission of this.
I'd agree that manga use of furigana helps (perhaps school-aged readers) reading, but furigana in novels are standard tools in the language that authors can use to achieve some effects that is hard to describe to non-speakers.