Right. I agree with most of what you said. However, that doesn't mean you can't build a platform that does what you described. In fact, and I'm not trying to self-promote here, but we've already done that. We're currently in beta going live in a couple of months.
> "If you're scheduling social posts without doing your due diligence on each and every platform within 2-4 hours of a post going live (preferably within 30 minutes before), you're doing it wrong."
Can you elaborate on this? What type of due diligence do you need?
> "If you're using the same post across multiple channels, you're doing it wrong."
Some posts can be shared as they are across multiple networks, other posts need to be different. We address this by allowing the user to write the post once and customized it for each network before its published. This includes different images, different URLs, different OG tags, keywords, mentions, etc.
> "If you're re-using the same post multiple times within a few weeks, you're doing it wrong."
When you publish something, only a percentage of your audience sees it, which is why it is considered a good strategy to repost every now and then for higher exposure. Just don't do it every few weeks. The way we solved this problem is by allowing the user to create category-based schedules. Basically, we have a content library that organizes posts by categories, and each category can have one or multiple publishing schedules. You can choose to recycle content from specific categories or not, up to you. The more content you have in each recyclable category the less frequent your content will be reposted.
There are many other hard problems that SMM platforms can help you solve including social listening, which if done manually can be very time consuming and silly.
EDIT: typo