"In 10 years time the buyer has half paid off the house, gained...

"In 10 years time the buyer has half paid off the house, gained anywhere from 30-100% in value (gains) was able to set up the family...and could go on forever"

According to http://www.yourmortgage.com.au

Borrowing $300,000 over 25 years @6.45%, after 10 years of $500/wk repayments they still have $232,000 left to pay off.

The only way to pay off half the loan in 10 years is to pay extra (every week for 10 years). Not every family can do that, especially if they want kids.