People have been complaining about laziness in language and "dumbing down" language since language has existed. It's nothing new and it's not happening at a different rate than before. The perceived degredation of language is not, and has never been, a real thing. It's natural and unstoppable language change. It's the reason you can't understand Old English, and why Hindi, German, Spanish, and Russian are different languages from English now.
That being said, things like this theoretically could help to increase literacy rates significantly in populations with low literacy (in a similar way Simplified Chinese script along with Chinese education reforms drastically improved China's literacy rates) – and most of the US has surprisingly low literacy (about 54% of adults have low English literacy and 21% are illiterate) – or for people who aren't proficient enough readers to gain anything from reading something of such a high level. Reading should be accessible to as many people as possible, not gatekeeped. It would be far better as some sort of "annotation creator" though probably, if your goal is more literacy.
Of course, you shouldn't rely on something like this by any means. But it's not bad for a lot of purposes, we shouldn't beat uneducated people while they're down. And either way your literacy really doesn't affect your "stupidity", although a lot of resources with knowledge you might want will require a certain level of literacy.
Considering China's literacy rate grew from 20 percent in 1956 to 65 percent in 1982 (and now 97% in 2020 which is insane for such a highly rural country – 43% of the population, to give an idea) due to them focusing on Simplified Chinese, you're just wrong in stating it "didn't do anything". In fact, Mao got the idea from seeing Japan's success in improving literacy by simplifying Kanji into Shinjitai, so you're wrong twice...
Of course, it went hand-and-hand with the government's education reforms, it doesn't deserve all the credit. But it helped a LOT. It can be argued that it's no longer a factor because of the access to education Chinese have now, and I'd agree, but it helped when literacy was in need of improvement.
Obviously though, different characters is a small change compared to completely rewriting the sentences to simplify it, like this does here.
I don't know if it makes you smarter, but I'd gamble you're more knowledgeable.
None of this matters though because the people who would read a dumbed down version of a book would have probably used a different shortcut if this weren't possible.
I love how someone who knows what they're talking about gets downvoted here. Don't you know you're just wrong and should keep your facts to yourself?! 🤦♂️
Linguists aren't behavioral psychologists or K-12 educators. Being challenged by unfamiliar language is an incredibly important experience in developing reading comprehension. It's not that a bigger vocabulary makes you smarter, it's that the process of understanding more complex language helps you both understand and formulate more complex ideas.
If you can't understand something, you don't get challenged, you just skip it. You need to be getting 98%-99% of the text to gain something from reading it