SBD created to fund the SPS (treasury) doesn't increase debt in any real sense (though it does increase the apparent debt ratio used by the blockchain to calculate the conversion haircut), until stakeholders vote to pay out those SBD in order to fund proposals, since it doesn't circulate, it just sits in the treasury.

If that happens (funding payouts), then one can conclude the stakeholders believe that such an increase is 'worth it'. Indeed funding something like @sbdpotato out of SPS is another way for stakeholders to place controls over the debt ratio (since @sbdpotato will destroy more SBD than the SBD put into circulation to fund it).

For this reason, as well as the funding rate being rather low (less than 1% of market cap per year), it was seen as fine to continue to fund SPS with SBD regardless of the debt ratio.