Not including rent is giving you a false figure.
eg. a $250k PPOR with $250k mortgage @ 7% = $17.5k + $2k (water and council) = $19.5k holding costs
So yes, that's 19.5/250 = 7.8% rise needed per year.
But if you rented it out instead, you wouldn't have $0 cost of living elsewhere. Your rent elsewhere if you didn't own your PPOR might be $280pw = $14,560 per year. You need to take that off your PPOR cost, so to own your PPOR as opposed to renting somewhere else is actually only costing you an extra $4,940 per year - so really only 1.98% rise needed per year.
Simplified example, but it gives you the gist.