Maybe the term "Marketing" wasn't the best in this context. Let me rephrase my point.
"Omnichannel experience" is a very broad field with a lot of different aspects you can and should consider. AEM is solution which you can use to satisfy some/most/all (?) of these aspects. And as always there are a lot of ways how you can approach these aspects with AEM and the Adobe Marketing Suite. But as you already said, this discussion is very open-ended, and there will not be any kind of definitive answer for them.
That said, I think that you get the best responses in this forum if you have specific questions to a certain aspect of AEM or AEM project. My experience is, that these questions get quickly and in most cases quite accurate answers here. But if you have very generic questions you rarely get an answer you can work with. I think that it's the wrong audience here, which is not used to respond to such kind of questions.
this is a more technical forum, where you have a lot of people which are able to answer a lot of questions regarding developing, debugging or troubleshooting AEM or AEM applications.
Your question goes more into a marketing-like discussion, how one could position AEM (and probably the larger Adobe Marketing Cloud) in that Omnichannel experience. I don't think that you reach the right audience here which is able to answer that question. I don't know if there is any forum out there where you can specificly discuss this topic with the right audience, but I would recommend you to post this question on LinkedIn in a relevant group. Maybe you get more and better answers there.
kind regards, Jörg, tech nerd and not capable to answer this question