If you pay 50% of a mortgage off and then default on later payments, can you get repossessed?

I am asking out of curiosity so this doesn't apply to me personally. If you pay 50% of a mortgage off, but then run into difficulties to pay the rest, can your house still get repossessed? Technically, you a) fully own the house and b) have paid half of the mortgage and will repay the rest when you get the chance. To me it seems ethically bankrupt for a bank to repossess you, no matter how many payments you miss. it would make more sense for the bank to already OWN the house and the mortgage holder to buy back the banks share from the bank. this is more ethically valid, saves time, costs and spreads the risk. that would also stop the present meltdown that exists now. thanks in advance