Aren't the scaling issues more in the send-to-all cateogry than in the person-to-person? Aka - a scoble broadcast out to 20,000 different endpoints causes chal

Aren't the scaling issues more in the send-to-all cateogry than in the person-to-person? Aka - a scoble broadcast out to 20,000 different endpoints causes challenges - whether it's pushed or pulled..