Yeah, Hasbro markets it as Ages 5+, I guess because they don't want to restrict the sales of the toy only to mature collectors. But Takara(TOMY) markets it at Ages 15 and Up, and it's Takara(TOMY) who have designed all the Masterpiece Transformer toy moulds thus far -- Hasbro basically releases their own version later on and are happy to let kids be totally stumped by a toy that was originally intended to be played by teens and adults.

If you have any Japanese Masterpiece toys, have a look around the legal blurb and you'll see 対象年齢15歳以上 or 対象年齢15才以上 (Ages 15+) -- even if you can't read Japanese at all you'll be able to see the Hindu-Arabic numerals "15" in the middle of a string of Kanji. This is Amazon Japan's page for Masterpiece Bluestreak, and if you look beneath the main image under "Product Features" the second dot point says 対象年齢 :15歳から (Age range: from age 15)