Was the world so technologically advanced thanks to Kyuube's race?

Question

It appears that Madoka's actions changed the world so much that the high-tech school and everything were no longer during the finale of the series. The Kyuube which contacted the girls wasn't seen by other people, so I wonder how the high-tech stuff came to be.

Answer 1

[...] the high-tech school and everything were no longer during the finale of the series.

I don't think this is actually the case. You're right that we weren't shown the school at any point after Madoka made her wish, but we still have very good reason to believe that humanity still reaped all the benefits from its relationship with the Incubators.

Recall the events of episode 11, following Sayaka's funeral, when Kyuubey explains to Madoka everything about the long relationship between mankind and the Incubators.

MADOKA: もしもあなたたちがこの星に来ていなかったら…
KYUUBEY: 君たちは今でも裸で洞穴で住んでたんじゃないかな。

MADOKA: If you had never come to this planet...
KYUUBEY: You'd probably still be naked, living in caves.

Clearly, the people of Mitakihara aren't living in the Stone Age after Madoka made her wish - and so I think it is best to conclude that mankind still benefited from their relationship with the Incubators in the final timeline just as much as they did in previous timelines.

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Of course, if you look at the mechanics of the way the Incubators operate, I think this should be obvious, too - the way the Incubators help mankind advance is by allowing people to make wishes and use magic. This is true both before and after Madoka's wish. While some girls certainly would wish for mundane things like healing some dude's arm and do little of wider consequence, others would wish for and do things on a grander scale.

Some, like Madoka, would literally change the universe. Others would do great things to move mankind forward. During Kyuubey's episode 11 explanation, we see images of magical girls, some of which look very much like real-life figures, e.g. Cleopatra, Joan of Arc, etc., who indeed are known to have done great things. In fact, Kyuubey explicitly states:

KYUUBEY: 中には歴史に転機をもたらし、社会を新しいステージへと導いた子もいた。
KYUUBEY: Among them were those who changed history, and brought human society to a higher level.

The implication being, of course, that they were only able to do that thanks to the wish and the power of magic they were granted by the Incubators. In sum, yes - the world is only so technologically advanced thanks to Kyuubey's race.