This was spawned by something @surreality was saying in another thread. The 'Because magic' excuse is a common one and we see it used positively and negatively. The latter happens seemingly most often (in regards to it being negative / noticeable) when Staff outright has no answer and just doesn't want to deal. This is, in my opinion, the biggest weakness of an original theme game (that involves magic). We've discussed it before: original themes take work and a lot of it. Players will come up and approach things you hadn't yet considered. You can spend a year fleshing out a theme, building a game, and two days after the gates open... you have twenty jerbs to answer with things you never considered.
Look at all the 'fan theories' that abound for well-established properties, like Harry Potter. Almost always about things that don't come up nor have reason to in the main series.
The 'because magic' excuse is used often - notably when it comes to technology - and to varying degrees of success.
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Harry Potter: It's never fully explained. The best explanation we have from the books and JK is that the wizarding world doesn't use technology because magic fulfills all they need. Where this falls flat is with the Muggle-borns. There's been vague assumptions that technology and magic don't mesh, but we've never seen a truly, totally concrete answer on it (unless it's in some JK tweet I haven't seen yet).
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Dresden Files: This is where the assumption above comes from, likely. Dresden, for example, drives an old VW bug because his magic interferes with computers, so he has to drive a car without one. There's no real 'science' behind it, but it's at least made clear: he doesn't use tech because it doesn't play nice with magic.
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Peter Grant: If you haven't read these yet (Rivers of London is the first) and like the above, you should. They're like this lovely melding of the above two with one of the most enjoyable protags I've read. Anyway... Peter Grant, new wizard, finds that his cellphone gets fried when he uses magic. The chips in it literally disintegrate. So what does he do? He experiments. He tests range, intensity, etc.. I loved this and it really helped enrich the 'because magic' concept of anti-tech (Peter, for example, has to setup a 'tech cave' outside the main building he and Nightingale live in, so he can still do his police work or catch a football game).
It's one of the things I've studied. The 'because magic' excuse. You can't just handwave it because readers (players) will notice. Because it will vex them. Because it will ruin their immersion.
In HP, the balance of 'they don't use tech because magic does whatever they need' is there, so it's not as big a deal. In Peter Grant, the explanation is given that magic draws energy and the chips and resistors in devices like phones and computers are the first to go. The reasons are given (even if not in nitty-gritty detail) and it makes the world all that much richer.
Does every third born in a city grow an extra nipple in your setting? Why? 'Because magic' is vague and underwhelming, but 'Because a wizard cursed the family that founded the original settlement' gives something concrete and it adds just that more flavor to the world.
I think this goes for a lot of things and it's part of why original theme games are so few and far between now. I've got a world building worksheet that I used on one of my more established personal settings and even it left me just sitting there at times thinking 'I never once considered this,' even though I acknowledge that while a particular society's historical methods of entertainment may not be important to me right now, it could be later and it would definitely be important to someone playing someone in that world.