I don't think that's very fair. US gamers are no more biased or living in a bubble than gamers from any other region in the world. American gamers could just as well shake their head at European gamers for not being very familiar with other highly regarded, influential games. I mean, The Oregon Trail was just inducted. Would the average European gamer have any familiarity with that? Generally speaking, gamers know what is made available to them and what's popular in their region. The BBC Micro is a British computer, and while it was sold in the US, it was not remotely the success here as it was in Europe. Americans weren't adverse to computer gaming in the 80s, it just wasn't nearly as popular as it was in Europe. Part of that is the cost and know-how involved in computer gaming versus picking up a console, and another part is the huge popularity of the 2600 and the NES in the US. But we have our well-known PC games from that era. Again, there's The Oregon Trail. It was developed in the 70s, and starting by the mid-80s, it was in schools everywhere. Outside of educational games, there's Ultima, Wizardry, King's Quest, etc. Plenty of computer games were popular in the US in the 80s, even if they were lesser successes than, say, Mario and more for "hardcore" gamers.
But yeah, ask a Western gamer, American or European, about, say, Tengai Makyou and they'll probably just reply with "Huh? What's that?" even though Tengai Makyou II is one of the most popular, highly regarded RPGs in Japanese gaming history. Heck, ask about the PC Engine in general. Among Japanese, American, and European gamers, Europeans would surely be the most ignorant of it. And as far as I'm concerned, that's just fine. As long as gamers aren't spreading misinformation, it's okay to not be knowledgeable about everything. It's not necessarily a result of closed-mindedness, as in a refusal to learn or try out unfamiliar games. We all have limited time and energy to invest in what is just a hobby, and it's not unreasonable to want to spend it on games you already love or games that have already caught your interest. And those are largely determined by the availability and popularity of a game in your region.