The concept does involve complete loss of agency but the reality is it's roleplay or poetic license. Slavery is illegal. When somebody calls themselves an office slave have they lost all control of lives. Ask somebody who calls themselves a slave a few simple questions about their everyday lives. Do bdsm slaves have a bank account and manage their finances. How are decisions on vacations, restaurants, furniture etc taken. What happens if you are not in the mood for sex and the master is. I;m sure you will find they are just like a married couple who call themselves master and slave. Your perception may not be skewed, It may be the information being given to you is skewed.

Numinosity post was largely off topic. You posed 2 clear questions and instead of addressing them he raised a totally different issue, which in my view is off base. Love and caring is to be expected in all relationships but is not required for something to be considered bdsm. Many bdsm'ers play with people they barely know. There is no love or particular care there any more than there is with any casual sex. If somebody says to a stranger please whip my ass for 5 minutes then leave me, would Numinosity question whether that was bdsm.

The trust aspect is just common sense part of Sane Safe Consensual. You need to know the partner isn't a mad axeman. But this is no different than normal sexual activity other than the nature of the activities is more dangerous so more can go wrong either by accident or design,

To be honest I do not follow your predicament or longing. Control yet not impede freedom is not an unusual concept or desire. Control can be done by dis/en couraging just like parent or teachers do over children. It can be done in a mock master manner eg "I forbid you to smoke that cigarette or wear that make up". But if the slave said "Screw you I'm doing it anyway" there is little the master can do. The aura of control "I forbid" is more powerful than a simple "Please dont". It is largely an illusion but illusions can be powerful and real.