Yes, it is the same as "seems" and "seems to be". So he might have said "I find chess too simple to be useful." The "to be" doesn't add anything really to the meaning. Does that help?

You are comparing these two sentences: "I found it simple" "I found it to be simple". I removed all the other words, because they do not influence the answer to your question. In the first, "simple" is an adjective modifying "it". In the second, "to be simple" is an infinitive clause that behaves as an adjective modifying "it". The difference is that "to be simple" is more abstract than "simple". It's the difference between simplicity and the IDEA of the simplicity. In practical terms, the difference doesn't matter, but if you are a person who enjoys thinking about things, it matters. Imagine if Shakespeare had written "Will I be or will I not be, that is the question". It doesn't have quite the same profundity as "To be or not to be", does it? Hamlet was thinking deeply so he needed to use the infinitive to express that he was thinking about the IDEA of being. Another possibility is "being": "I found it being simple". It is another alternative with another shade of meaning.