Fees need to adapt to the ever changing reality of the system and could not possibly be forced or determined through any algorithm.
The Blockstream plan is to FORCE a particular capacity, by setting the block size limit in the consensus rules, and then let the fees "naturally" adapt to that artificially constrained capacity.
Why is that better than forcing the fee directly, and ensuring that the capacity is well above the demand? (I ca think of several reasons why it is much worse.)
Is it possible that the devs do not see that their plan is just as "ideologically impure" as setting the fee directly?