You are correct. I did this for the first time in April of this year. We stayed at Wyndham Bonnet Creek because it looked (and was) so fabulous. So much more room, great pools and lazy rivers and less than 1/10 the price it would have been on Disney property for 6 of us.
But we do like the early ADR and FP ability of onsite. We also like the convenience of magicbands for charging. So I gave Disney their pound of flesh, paid $75 per night for the advantages and it was the best of both worlds. Still saved me tons of money.
Felt guilty tying up a site that wasn't used, but not as guilty as if we booked, got the early bookings for ADR and FP and then cancelled, as others had suggested.