I’ve never really paid much attention to or trusted presence status, with the exception of statuses that are manually set (e.g. do not disturb in Slack and similar).
It’s kind of funny, considering that presence is probably the most challenging technical requirement for large-scale messaging platforms. I will say that my two most-used messaging platforms, iMessage and Slack, both usually do a great job of delivering push notifications to only the ideal device (my phone, tablet, or computer). My intuition is that this logic is roughly the same as presence.
I'm glad you've been blessed with whatever Apple Magic lets iMessage work across devices for you but between my iPad iPhone and MacBook all I can say is I follow up important messages with a phone call because it's one of the more unreliable and indecipherable systems I've never been able to figure out.
No going half-way into that ecosystem.
Facebook Messenger definitely does the best job. I believe it shows the delivery status of every single message.