A Boring Dystopia

What about cases where the move is only temporary?

In their initial phase, land contracts are, effectively, a rental agreement, including for short-term. (With one difference: the payment is fixed for the life of the agreement; it doesn't increase year over year) When "temporary" turns into "long term", (as it so often does) a land contract already has you covered, by locking rent through the initial phase, then gaining you equity through the final phase.

In the private lender case, do you see that as different from someone who starts their own company and manages the property themselves while the renter pays them directly?

Vastly. One includes conveyance of equity; the other does not.

The landlord/property manager retains 100% equity throughout the life of the rental agreement. The private lender retains only the value of the loan. With a land contract, the seller/lender retains 100% of the equity for a couple years, before the agreement automatically converts to a private mortgage.

The earning equity piece isn't necessarily incorrect, what the owner is losing is potentially the opportunity to move at all.

Completely false. Absolute worse case scenario, they abandon their equity and return title to the lender/seller. Terminating the loan/purchase agreement in this absolute worse case scenario is functionally identical to renting. At its best, renting gives you this outcome, and creates new, worst-case possibilities: where the landlord absconds with security deposits and charges additional fees.