[_delirium]

It's also not only scarcity, but academic-incentives-driven artificial scarcity: in the U.S. especially, many advancement committees have started using acceptance rate as a misguided proxy for "conference quality". So if you want people to see publishing in your conference as a valuable addition to their CVs, you need to have a <30% acceptance rate, preferably more like 10-15%, so you can be counted as a "very selective" conference. This is a bit silly, because acceptance rates are hugely influenced by submission pool, but it's how the institutional system currently works.