Anyone can testify anything, but I don't see how "having been a landlord" gives you any particular authority to say whether tenants commonly feel that landlords have power over them. (You might be able to say that your tenants didn't obviously-to-you feel that. If you knew them closely enough to be sure of being right, then that itself makes you a very non-typical landlord.)

I would not want to claim that anything nontrivial is true of all tenants or of all landlords. But the tenants I know who have said much to me about their experience of tenancy do in fact appear to feel that their landlords have power over them -- but there's a selection effect here: you're more likely to be talking to other people about your relations with your landlord if something's gone wrong somehow.