So I've just finished reading this whole thread and found it very useful, thanks y'all! I was already familiar with the general argument in favour of keeping a mortgage, but there was a lot of nuance and detail in here that was new to me, and it's also fascinating to see how mortgages work in different places.
I guess I belong in this club, having only paid the agreed monthly payment since spring 2014. When we first took it out, it felt awful to be in debt, although the amount was less than half the value of the home we bought. I was torn between "a mortgage is almost free money, we should stretch this out" and "we need to pay off this horrible thing as soon as possible". So I figured if I can't decide between these two courses of action, just paying the agreed amount is probably the best... And as soon as the amount dropped into five figures, it didn't feel horrible at all anymore.
Mortgages here are almost always variable rate, with a specific base rate (in our case the 6 month Euribor) + an agreed margin for the bank. This means that the rate changes every 6 months, but it's not something that's up to the bank. We pay the same amount every month, and if the rate goes up, the loan takes longer to pay (and if it goes down, the loan term gets shorter). So with this setup, banks wouldn't usually lend you money for 30 years, since the loan term has to be able to expand if rates go up. I think banks also don't really consider pensioners to be able to handle mortgage payments, so they'll only give you loans that end by the theoretical (very high, nowadays) national retirement age.
When we first took out the loan, the base rate was just above 0.4% and the bank's margin 1%. Since then, the base rate has dropped somewhere below -0.5%, and we've twice renegotiated the margin, first to 0.65% and then to 0.45% (I think the first of this was free and the second cost a few hundred euros). Since contracts currently include a clause that the bank will not pay the customer any interest, we now pay that 0.45% ... while smiling and thinking of this MMM club. Our original contract didn't include that clause, and I've heard that some customers have actually been in situations where the bank pays them to keep their mortgage! Meanwhile, the projected end date of the mortgage has moved from spring 2028 to summer 2027 because of the lower base rate and those renegotiations.
So it's possible to follow the DPOYM philosophy, even if you can't have a 30-year fixed loan. A combination of a much larger down payment and muuuch better rates does the trick just as well.