This logic is flawed.  They don't necessarily accept that the minimum is 0, they just want a reactive rate that doesn't require babysitting, and this is their only choice on bitfinex.  Most people use FRR hoping to catch uptrends (not realizing the FRR is terrible at reacting to uptrends).   If given the option to set a minimum, they almost all certainly would (there may be some who would set it to 0%, but not many.)

I also don't understand the resistance to this idea... Its easy to code, and adds a new feature that I'm sure people would appreciate. Default it to 0.0% if you think its manipulative (though I'd say that would be stupid because a 0% loan shouldn't ever go out anyways).  I'd also mention that it is a feature your competitor has.

(I will say I doubt this will have a huge effect on rates, since it wasn't in on day 1 and too many people already have their cash in FRR on set it and forget it mode, but I do think it would be a nice feature for people, and would at least get new users thinking about what they're willing to take, and maybe get them to understand FRR may go WAY BELOW what they actually are willing to accept.  My guess is most of the old money in FRR was from people who never put a second of thought into the rates maybe going this low.)