Is seller financing really taking off, or is that just the phrase of the month?

Buyer-pushed, mostly, from what I see on listings. The ones that say owner financing available in the description are usually properties that sat 90 or 120 days first. The seller didn't plan this, they ran out of cash buyers.

Not entirely. There's a second group and they're the ones who actually want it. Owner has held a duplex thirty years, basis is nearly nothing, and a cash sale means writing a very large check for gains in one year. Spreading it over ten years through installment reporting changes the arithmetic a lot. Those sellers go looking for a buyer who wants terms. They aren't distressed at all, they just don't want the tax bill landing all at once.

@anchor's group is the one I'd want to buy from, and it's the harder one to find. Tax-motivated sellers rarely advertise. They tend to already have a buyer in mind, a tenant, a nephew, a neighbor who farms the field. By the time it hits a listing site the reason is usually that the bank buyers didn't show up.

@rigging, on your actual question, I don't think the two markets stay separate. A seller who agreed reluctantly still ends up holding a note, and once they've held it for a year and seen the interest arrive they often stop describing it as a concession.

The free and clear part is what decides it. If there's a mortgage underneath, the seller's lender almost certainly has a due-on-sale clause and the whole thing gets complicated fast. Owners who hold clean are the ones who can actually say yes, and on land that's a big share of owners.

Something I've been chewing on: the growth story depends on rates staying where they are. If conventional financing gets easy again, the reluctant sellers stop offering terms overnight and you're left with only the tax-motivated ones. That's a much smaller pool. So whatever I learn about this now, I'd rather learn the parts that survive a rate drop, which is mostly the documentation and the vetting.

On land it never went away, which makes me skeptical that it's exploding so much as becoming visible. Rural acreage has been sold on contract for decades because banks won't lend on it at any rate. What's new is houses.

@arbor is right that the reluctant group evaporates if borrowing gets cheap. Though I'd add that the sellers who discover they like the monthly income don't necessarily go back either. A retired owner with a note paying above what a CD pays is not in a hurry.