don't ask me
it will have something to do with the steem architecture
you'll have to read up on white papers and steeminc explanations and witness explanations to get an answer for such questions
most people won't bother to ask such
it is how it is
there will be an explanation to your answer
if it is sufficient I don't know
it won't change regardless
That probably means that better blockchain social networks will be able to potentially do better than Steem someday if it has not already.