So what you're saying is, we should just believe the Church Fathers, etc.? Why not consider what the Marcionites believed? The question then becomes, what is the role of critical inquiry in all of this? Are we genuinely seeking a truthful understanding of the origins of Christianity? If so, what the Marcionites knew or claimed holds significant value. On the other hand, if we're convinced that the truth comes from divine inspiration or some "superior intellect" and we only use textual evidence to support a pre-existing belief, why engage in a discussion at all—except perhaps to gather new arguments and texts that reinforce that belief?The need for Luke's gospel is stated in 1:3 ("having carefully investigated everything from the beginning, it seemed good also to me to write an orderly account for you"). In other words, Luke was doing Theophilus a favor by "carefully investigating" the many accounts about Jesus that existed, so that he wouldn't have to sort through them all himself, the same way that Eusebius had "carefully investigated" earlier Christian writings and wrote an "orderly account" of Christian history for Christians of his time.
The Marcionites believed their tradition came first. The orthodox, of course, believed the same about theirs. To accept one side's claims without fully engaging with the other's perspective is a failure in scholarly responsibility. And if you're not committed to that kind of inquiry in the first place, by all means, continue doing whatever else it is you're doing.
I think that Marcionism is "truer" than the orthodox tradition because the Marcionite Paul resembles Moses. All sectarian leaders in the Biblical tradition, even Muhammad, end up having this resemblance. I don't find the Acts narrative to be compelling history. I don't find it reasonable to suppose that "all of Christianity" was in agreement about everything when Paul's own letters testify to the opposite situation. Celsus says otherwise. The Acts of the Apostles seems like second century fiction - if not propaganda.