Thanks. On your first question, it’s just an denominational dispute: We claim that Peter didn’t start their Church (or, if he did, they fell into apostasy and lost any authority they briefly had). Basically, the only direct evidence we have in that regard is Joseph Smith’s statements that he was told that the ‘true’ church wasn’t on the earth and instead needed to be restored.
For the second question, I can give you my answer, which starts wtih this: When I am not in-tune with God’s direct revelation, I’ll need to rely on someone who is. This is especially crucial (from my perspective) during repentance. Sometimes – either because of severity, complexity, or habit/addiction – a sin will obscure my ability to see a way out. Being cut off from the Spirit and without a clear route back, having another path to communicate with God will be essential.
I think also (in other circumstances) the tension between the two lines of revelation (direct and hierarchical) is useful in pushing us to prayerfully consider more deeply. If I simply accepted everything I felt/wanted as coming from God, I could very quickly be following a ‘god of my own creation’. Having a second path can help keep us in line (not, hopefully, through blind obedience but by reminding us of other answers to prayerfully consider).
I’m not sure I’ve articulated that well but hope it was helpful.
