Nobody can tell me what is the purpose of that "foundation fee on each block" ?

its like 6 DMD a day and its funding upkeep of DMD Diamond infrastructure
and pay bounties for work done for DMD Diamond
in fact its way to low to really allow push ahead development but its enought to keep core elements up and running
the POW foundation share will be removed with next wallet and replaced by another similar mechanism thats not linked to POW