I think you're mostly right here, Trapper. I've been digging in Acts lately myself and asking "what happened?" When Jesus was on Earth, He had the Twelve (we capitalize it now, not sure it should be...) with Him as His disciples. he had women, at least, with Him, and He had friends like Lazurus and his two sisters, Mary and Martha.
He gave them all instructions to tarry in Jerusalem until the Holy Spirit came, which it/He did, 40 days after the ascension. Peter gave that sermon and two or three thousand were saved that day. Hundreds and thousands more were saved on a daily basis right after that. Remember they were meeting daily to pray and eat together.
My imagination says the 12 disciples were so busy with logistics that they didn't have time to pray as much as they needed to, and maybe they weren't getting enough sleep or getting much time to go be alone with God like Jesus did. So they organized a hierarchy of men to help with the ministry.
Didn't something like this happen with Moses? His father in law Jethro told Moses to appoint some men to help, and things took an interesting turn after that?