The average user sees http://123.45.67.89/~sk/microsoft.com/techsupport as a legitimate Microsoft website. That's what this change is intended to fix: users that see a domain in any part of the URL as being valid. They want to change it to only show the part that's actually security relevant. If you tell the average user "Look for Microsoft in the URL", and they find it in the path, they're going to fall for a phishing scam.