From what you're saying, it sounds like components in this framework (React?) are not simple at all. A major hurdle in evolving a program is capturing and maintaining simplicity. The proof of whether something is simple lies in its composability, readability, and so on. If someone claims to have found a method of writing simple components, do not believe them if the simplicity is not evident. A truly simple solution would not be so burdened, and a somewhat simpler solution would be less burdened. Of course, simple still doesn't mean easy, because the Fast Fourier Transform may be simple, but I can't teach it to a 5 year old (or anyone, really).
Never religiously cling to statements such as "strictly separate presentation and content". These are all just guidelines to suggest simpler solutions, not hard rules that guarantee simplicity. They will sometimes be excepted.
There are such things as components, which compose strictly by interfaces and externalize separate details, but it is up to the programmers to realize them in their programs. Also, simplicity is a global property of a system. Nothing can be judged on simplicity in a vacuum.
All that being said, I don't have experience in web or UI in particular. Seems like logic is moreso a local thing, whereas presentation is moreso global (but may consider locally defined advice). State can be local or global.
You are mixing your terms. Complexity is another word for many. As such it is measurable objectively. The opposite, simplicity, means fewer.
Readability is highly subjective. At this point you are talking about what is easier for you. Easiness is not simplicity. Simplicity, in almost all cases, requires addition effort and that is not easy.
I did say that simple doesn't mean easy. I don't know how to judge whether something is many or few without a fixed norm, nor how to measure it without reference to the environment it exists within. Simplicity does not mean having so little to the point of unease.
"Everything should be as simple as possible, but not simpler"
- Einstein (probably[0])
Brainfuck is a simple language. A Brainfuck program written to parity with an existing non-Brainfuck program is likely complex. A musical note is simple, but a musical score may be highly complex.
Never religiously cling to statements such as "strictly separate presentation and content". These are all just guidelines to suggest simpler solutions, not hard rules that guarantee simplicity. They will sometimes be excepted.
There are such things as components, which compose strictly by interfaces and externalize separate details, but it is up to the programmers to realize them in their programs. Also, simplicity is a global property of a system. Nothing can be judged on simplicity in a vacuum.
All that being said, I don't have experience in web or UI in particular. Seems like logic is moreso a local thing, whereas presentation is moreso global (but may consider locally defined advice). State can be local or global.