To clarify, I believe the OP meant that it's somehow fitting or 'correct' that the stereotypical fantasy story takes place in the middle ages: y'know, swords and sorcery, kings and emperors; riding on horseback over hill and dale...that kind of scene.
As the #1 fan of science-fantasy, my answer is a loud and clear False. ^^; I have a devil's advocate argument for this statement, though...but first, let's take a vote:
So I'm pretty sure their argument was that this particular time period featured both the rapid development of what would become modern civilization, and a population that still commonly believed in magic IRL-- making it a perfect fit for the fantasy genre.
And to play devil's advocate, I would add that it was also a time with immense emphasis on learning a trade-- usually the only way out of a life of menial drudgery was to be born into the upper class, marry into the upper class...or master a complex skill that people would be willing to pay you to perform. The right apprenticeship could literally change your life...I'm sure you're already getting fantasy vibes just from reading this description. ^^
The idea of a young hero gaining access to a rare talent and using it to expand their experience of the world is a staple of fantasy fiction, and I believe it's a reflection of how life was back then. Whether your talent was intellectual, physical, or emotional, if you could hone that skill and become famous for it, you might gain the opportunity to see and do things that, normally, you would never be allowed to do.
The reason why I say False, and why I love fantasy set in the present, the distant future, and on totally alien worlds, is because I think those limitations can exist anywhere.
Societal barriers requiring you to have special graces or skills to advance to greater opportunities still exist even now-- that concept hasn't gone away, despite capitalism's best efforts to make us believe it has. ^^;
And although 'learning a trade' is now just considered Plan B if you can't go to college like a 'normal' person, I think there's still magic in gaining a specialized skill, and people will see it immediately if you call their attention to it. Just thinking about how my fellow scientists react when I say I'm an artist, or how my fellow artists react when I say I'm a scientist-- it's clear to me that people are still mystified by rare skills, even just slightly rare ones.
I think the only difference is, these days you're expected to assimilate completely into the community of whatever singular skill you do have, becoming one of a faceless collective drawn on by society at large. Like, we don't think in terms of a 'town scientist' or a 'village artist' that we approach for expertise; we think of 'scientists' and 'artists' who exist somewhere in the background of our lives, only very rarely interacting with 'normal' people. I guess that speaks to just how much bigger the world has gotten. ^^;
And personally, I think, in an age where technology continually advances towards walled-gardens (i.e. tech that is 'opaque', discouraging users from knowing anything about how it works or how it can be modified) and becomes more prevalent in all areas of life, new conventions of fantasy may form around it, seeing 'magic' in people who can break down those walls and actually manipulate the paradigms we live in.
Basically, I think hackers are cool in the exact same way wizards are cool, and if my predictions come true and other people start to share that viewpoint, science-fantasy will probably become just as popular as traditional fantasy someday. 