The magical community was always more intelligent and further evolved than the mundane one. But the mundane manages to catch up a lot, and even becomes a threat to the magical world. Based on that, the world between magical and mundane was completely split, with the help of excessive usage of obliviation spells. Mundane lost knowledge about magicals, but the magicals stayed out of touch of technology as well.
For thousands of years, magicals traditionally considered technology the way a stern parent might consider a child's finger painting — endearing at best, a waste of time at worst. It had been rather a shock then, when the European renaissance gave way to the enlightenment, and the finger paintings suddenly flashed into technical drawings for iron foundries, guns, star charts, and more. The wizards watched with growing uncertainty as their non-magical brethren enthusiastically unraveled the non-magical components of alchemy, and published journal after journal, dreaming of ever greater and greater feats,
In the end, one wizard was all it took. One wizard barging into the ICW main conference hall, waving a just-published copy of Sir Isaac Newton's Principia Mathematica, the ramifications of which were clear to every present disciple of the magical art of arithmancy. For two whole years, the world balanced on a seesaw. A tiny force either way could have pushed the balance. But it just so happened that the wizarding world was fresh off the challenge of obliterating divination magics from the world, and thus had no shortage of memory altering expertise at the ready for the greatest mind control project the world would ever know — the enacting of the international statute of secrecy.
Such a draconically enforced cultural divide was not without it's consequences. While the muggle world lost much of the knowledge of the magical world, surviving only in myth and story, so too did the magical world lose touch with the technological forces that had originally driven a wedge between the two worlds. But so long as muggleborns were removed from the muggle world at the age of eleven, and their parents subtly persuaded not to get involved, none of this mattered.