It is very relevant, but also very difficult to pull off. You need to be correct that there is even a potential market for what you want to sell and you need to come up with something or package something in a compelling way no one has thought of before. The best example is probably the Nintendo Wii and Nintendo 3DS. They actually came out and talked about Blue Ocean when launching it. I don't know if they were thinking about the strategy when designing the products, but they correctly assessed that the market was not core gamers but people who usually do not even play games. That is a pretty bold gamble.
Hard to tell if it’s such a gamble considering all their prior consoles were aimed that way as well. If anything, the gamble was in not making the move towards “hardcore gamers” that everyone else was making at the time. They had their established idea of reality and they didn’t cave into what everyone else was pursuing. Such insight can be a unique asset itself.
Which, your point stands nevertheless. You have to have some level of deeper understanding of and experience with a market to pull it off. Having some sort of philosophy and principles probably don’t hurt either.
Edit: It appears this content/article/paper was written almost 20 years ago. Interesting.
https://www.blueoceanstrategy.com/what-is-blue-ocean-strateg...