> That feels absolutely insane to me, especially when you consider that by the time you built up significant amounts of equity you'll have significant commitments (eg. college age kids) and/or be close to retirement. Going 3x on S&P500 might be justified when you're a new grad, but not beyond your 30s.

I don’t know about the US situation, and while I generally agree with you, home loans (in Canada) are nice for a couple reasons 1) the rate is better than you’ll get anywhere else, so you can significantly cut down on an emergency fund to stay invested (or even savings in general - e.g. you can keep invested in the market to drive your old car until it dies, get a dealer’s best price with their kickback from a bank on a new car, pay off the bank loan with a low-interest HELOC, then pay off the HELOC over the next several months) and 2) the interest on home equity lines of credit is tax deductible if used in various circumstances when you’ve already exhausted your other tax-advantaged options. (Conversely, mortgage interest is not tax deductible here.)