Asides from ifconfig not being maintained (which is reason enough not to use it), I always wondered specifically what was broken with it.

Then I worked for an arbitrage desk at an investment bank. They used virtual addresses for different IPs, on top of vlans connected to different exchanges, redundantly (ie bonded).

Not a single IP-having interface appeared using ifconfig.

OT but ip is a really unfortunate name that will be hard to google for.