You’re making the mistake of thinking that writing is about adequate communication. It’s not, or not only. It’s also about signalling that you had enough slack / wealth to waste tons of your educational time and effort learning arbitrary rules, and thus that you are probably 1. somewhat disciplined 2. somewhat well-educated and 3. part of the elite, or at least not a total prole. This is how complex writing systems have survived so long.
You’re making the mistake of thinking that writing is about adequate communication. It’s not, or not only. It’s also about signalling that you had enough slack / wealth to waste tons of your educational time and effort learning arbitrary rules, and thus that you are probably 1. somewhat disciplined 2. somewhat well-educated and 3. part of the elite, or at least not a total prole. This is how complex writing systems have survived so long.