Fate Series (Nasuverse) - The Age of the Gods ended in 700 BC, and with it marked the beginning of the end for Magecraft. Ever since then, Magic has gotten progressively weaker as mankind moves away from mysticism and esoterica and towards science and technology. Even the most powerful magic usable by modern Mages are but parlor tricks compared to what could’ve been done in the age of the Gods, and magic has gotten progressively weaker and weaker as the decades go on. The entire reason Servants are as powerful as they are is because they’re from a time when magic was significantly more powerful than anything in modern times, and even then many Servants pale in comparison to what they could have done as their true historical selves.

Mage: The Ascension (World of Darkness) - The Order of Reason, now known as the Technocratic Union, was established in  to maintain order and scientific enlightenment, and thanks to them humanity has progressed away from the supernatural and towards rationality, stamping out magic in the process, and without the belief that magic even exists, magic has gone further and further to the fringes of the world. It’s gotten to the point where even basic spells can break reality if performed in front of “muggles”, as humanity has progressed so far away from magic that even seeing it shatters their understanding of the universe.

Magic is dying, and science has replaced it