Ah, OK.
Even so, though, it doesn't actually make magecraft impossible, just obsolete, and it doesn't prevent the ultimate goal of magi, which is to reach Akasha.
Certainly there are magi who would nevertheless oppose it, but I wouldn't expect the nicer magi like Rin to do so. She has no desire to hold back the rest of humanity just so she can be superior to them. And, some magi would outright support it, particularly the ones with specific goals. For example, I would expect Zouken to be on humanity's side there, since he could use the technology to gain immortality.