Muggles generally came into the wizarding world with their spouses. Most knew their places (no more than three feet away from their spouses), and what was expected of them (keep quiet and tell no one about the wizarding world). Some did not; some stuck out like an American tourist at High Tea, and treated the wizarding world as a freak show, or worse, as if it were some third world country ripe for exploiting.(...)

But now the birthrate of Mudbloods was rising alarmingly. And with Mudbloods came more Muggles and greater threats to the wizarding world.

Mudblood students brought their Muggle family members into Diagon Alley, where the prices of unicorn horns and other commodities were forced up due to the purchases of those who had no appreciation of the "souvenirs" they were buying; such commodities were becoming scarce, affecting the wizarding world's economy and its ability to meet demands. Mudblood students were also polluting the ancient customs and traditions with their Muggle music, clothing, customs, slang, diseases, addictions and generally disrespectful attitudes. Lucius had some investments in Muggle companies, but his were drops in the huge ocean of international commerce. Some parents of Mudbloods had sought to purchase businesses or become "silent partners", further affecting the wizarding world by not remaining silent on how businesses should be conducted. Imagine cheap ballpoint pens in Hogwarts.