To be fair to Steemit Inc. , they had done their best to make the whole thing pretty simple.
If SBD = $1, the whole consideration is 100 percent true. For a $100 payout, 37.5 SBD will mean $37.5 and the value of rewarded SP will also be exactly $37.5 (it still is). Curation rewards will also be equal to $25 in value.
But they did not factor in the huge presence of SBD on external exchanges which could be, and has been, subject to massive buy orders.
As far as the reward distribution algorithm is concerned, it cannot be simplified without making major changes (hardfork) and, probably, causing a huge wave of shock and reaction.