In Chinese for instance, you can use a keyboard that combines radicals - parts of a character, or you can use a keyboard that combines phonemes. Those seem likely to change literally how you think in your language. There may be related concerns for Arabic.
That said, one of the complaints in the blog is that two different codepoints render to the same exact letter / phrase / word — this is not a problem unique to Arabic in Unicode, and there are known approaches: I’d expect (I’m not a Unicode expert by any means) that more work on the tech stack for rectification (I’m sure there’s a technical Unicode word for this process of matching codepoints for e.g. search and uniqueness of rendering) would likely be useful for Arabic, and relatively seamlessly flow in many places.
That’d be Unicode Normalization. I don’t have an opinion on the best source for more details, so here’s a link from unicode.org https://www.unicode.org/reports/tr15/
I don’t know enough to know whether or not there are still Arabic-specific issues, either in the spec or the implementations.
The example in the article of copy/paste/search is interesting. I think it’s equally likely to be a RtL issue as a normalization bug, but I haven’t done anything significant with either topic.
In both cases, the original plan was for Chinese characters to fall out of use entirely via gradual simplifications, but in both cases the simplifications stopped soon after the first planned stages and it seems very unlikely it would be a popular initiative at this stage. Basically what happened in both cases was the equivalent of a spelling reform, not the elimination of a writing system.
In the case of Japanese, it seems there is some regret around simplification because characters not in the 常用漢字表 do not have the component simplifications applied that the standardised characters do (for instance, 攪拌 is more commonly used than 撹拌 despite the 覚 component being the "modern" simplified form -- and there are characters with no simplified form like the first character in 艱難, first character in 辻褄, or 迄).
There was a theory in the XIX / early XX century that full literacy was impossible without the Latin script but such claims are ridiculous especially for Arabic which is an alphabetic script already. China has higher literacy rates than Vietnam, for example.
I don't think the many composition rules of Unicode are really necessary, though. Maybe as an extension for academic work or artistic compositions but not for computing.
If all we had were movable types, all of these language users would find a way to write their language that wouldn't require a Turing-complete computer on each glyph. Now the Unicode gods pander to some of these computer-hostile scripts making the users of different scripts feel slighted.