Let's take a real look at that.
Consider a 20 year mortgage, $200K @ 3.5% ('worse' than your 3.0% example), monthly payments are $1,160. $13,920 annual.
Before I continue, I'll point out that your
"(assuming any dividends are consumed by other living expenses)" is double-counting. If you didn't have the mortgage, you would not have the $200,000 invested to provide divs for other living expenses either, so cross that, in both cases those expenses need to be paid out of other sources.
https://www.crestmontresearch.com/docs/Stock-20-Yr-Returns.pdf
Zooming in, I estimate year 2018 to have returned 6.67% ( 5% plus ~ 1/3rd of the next 5% line), the lowest in recent history. That conveniently puts us right on the border of the lowest 10% and 20% decile points, so that makes a pretty good 'bad-case' scenario; worse than ~ 90% of history.
We can back test this here:
https://www.portfoliovisualizer.com/backtest-portfolio#analysisResults
This shortened link shows you that a 75/25 Asset Allocation (pretty typical for someone in the accumulation phase of life, and accepts your premise that most people are not 100% stocks) returned ~ 6.38% annualized (with annual re-balance), in-line with our market return estimate of 6.67%:
http://bit.ly/2Zd0LNG
The tool let's you adjust for deposits/withdrawals, so here is a short link with a monthly $1,160 withdrawal (fixed, no inflation adjustment to match a fixed rate mortgage):
http://bit.ly/2ZeoAVc
At the end of 20 years, the mortgage is paid off, you both have 100% equity in the house, but
the mortgage holder has $100,098 additional money in their portfolio.
And this is a 'bad-case' scenario. 90% of the time periods in history were better, many far, far better. And the worst ones were not so far down from that.
If I take a recent 'good-case' (but far from the best - it looks to be close to median returns), 1994-2014, the mortgage holder ends up with an astounding $460,535 additional money in their portfolio!