So those who are paying off their mortgage, should not be focused on Early Retirement as you can't get there without the stock market performing at least as good as the worst 30 year stretch, which happens to be over 7%. This is the same logic on why you can't retire early if all of your investments are in cash. If you are betting on the stock market to reflect an return of less than 3% pre inflation return over the next 30 years, then you are by definition expecting there to be deflation. If you believe that deflation is in the future, then you should not own a house or other assets as they will decrease in value over the future and hurt your chances of retiring.
It depends on one's path towards retirement. I think the markets are likely to be iffy at best during my remaining life, so I've been focusing on productive property investments that keep my cost of living as low as possible once I semi-retire or fully retire or whatever it is I'm planning to call it.
So, solar, gardens, greenhouses, water storage, etc - and, in the case of solar, I'm oversizing it somewhat with money now, so I can either bank kWh going forward, still be ~0 power bill as the panels degrade, power an electric car, or some combination of all of those - so by effective prepaying my power bill for (ideally) the next 50+ years, I reduce my uncertainty going forward. I'm also planning to go with string inverters over micro inverters, so I can hook up a battery bank if I see the need for that in the future (being able to run fully or partially off grid). And have copper run so I can interconnect my various systems if needed (my office is currently totally off grid, and I'd like to be able to power basics in the house from there if needed - which does mean I need to snag a two phase inverter for out there at some point).
Same is true for the gardens and greenhouses. I'm working towards being able to,
if required, meet most of my needs immediately on the property, with a surplus to trade/sell/take care of family/etc. I'd like to be able to live comfortably on under $10k/yr, if I need to. I'd prefer to have more coming in and spend more, but I'm aiming for the ability to run extremely inexpensively as an option.
I disagree that the markets are the only path towards early retirement, and am working towards proving that theory.
Nations and currencies go through their arcs and decay, and I'd rather still be flexible if something happens to the dollar (which I consider to be a reasonable enough chance during my expected remaining 60 years or so to be worth considering). This is part of why I keep a non-trivial chunk of value in not-dollars as well (including bitcoin, because why not?).
I agree that looking backwards, tossing everything into the stock markets makes sense, but past returns are no guarantee of future performance and all that, and I see some impressive storms on the horizon that make me question the next 5 decades of market performance.
Maybe I'm wrong and I'd have been better off in the markets. Oh well. I do have money in the markets, and if that performs nicely, awesome bonus. I'd rather be heavily diversified in paths to not needing a full time job (technically, I'm already there as I work part time), but if one of the variety of things I think are possible in my lifetime comes to pass, I'd rather have put some effort into hedging against that, such that it leaves me in a better place after that event.
As far as deflation and not owning assets goes, a paid off house is an entirely reasonable thing to, you know, live in. I don't expect it to appreciate over time, as I'm not in a crowded coastal city. I expect it to decrease in value over time as it gets older, but I intend to keep living in it for the rest of my life.
Also, the mortgage question is irrelevant to me as I wasn't able to get one anyway...