More existing SBD means each of them backed by less STEEM. Even if the SBD isn't being paid out they still affect market price. Reducing SBD supply is why @sbdpotato is a thing in the first place and this is counterproductive to that, now along with countering SBD printing from inflation @sbdpotato also needs to counter SBD printing from @threespeak videos.
If not set to @sbdpotato, the video rewards beneficiary is better off sent to @null in my opinion.
Proposal to directly burn SBD from @steem.dao is great way to reduce SBD supply but if it's funded it will interfere with other funded proposal (if my understanding on how the DAO work is correct). Getting it funded in the first place is also very unlikely.
That is a good point, although the magnitude is unclear. I would say that SBD which is paid out and circulates has a much greater impact, but I can't quantify this or prove it. In any case, the numbers are currently very small. See below.
Only to the extent that:
Currently the maximum DAO payout rate is about 1700 SBD per day and active payouts is only 230 SBD per day. So clearly there is ample opportunity to reduce the size of the DAO fund with burn without affecting other payouts, if desired.
Currently the DAO fund is about 170K SBD out of 7.3M SBD total, so the DAO is really negligible when it comes to the backing ratio. In the future that might not be true, in which case I would expect increased interest in some DAO fund burns, or funding things like @sbdpotato from the DAO.
I agree with everything you said here.
Ultimately the decision is in the hands of @threespeak. Hopefully this comment chain will give them some grounds for considerations.