Ah - but I have. I’ve studied the “synoptic problem” intermittently since I was a teenager, have read a good bit of scholarly literature on it, and am also aware (as perhaps you are not) that any consensus there was has pretty well dissipated over the last 20 years or more, as the shortcomings of the old source-critical approach and its offshoots have become undeniable. One effect of that collapse has been to make even earlier dates for the gospel more plausible (as in John Wenham, to name just one source).
That is why detailed studies of the historical background have become far more common (for example, Hurtado, N T Wright, Craig Keener), together with better studies of narrative transmission (as, for example, in Richard Bauckham, specialising in eye-witness testimony and how it operates). Bauckham also initiated work on using the frequency of personal names to date the gospels as history-biographies firmly in the early to mid 1st century, work that is also picked up in the work of Peter Williams cited somewhere in the thread - incidentally, Josh and I had a good conversation with the latter when we were in Cambridge recently, at one of the world centres of New Testament historical study.
Other recent work has explored the genre of all four gospels, and how they follow (to varying degrees) the accepted methods of 1st century historiography and biography.
When it comes down to it, the “synoptic problem” was an artifact of trying to analyse the gospels too precisely with inadequate information and limited “modern” tools. There is neither sufficient historical information, nor are the gospels long enough, ever to reconstruct exactly how they relate to each other. But increasingly, mainstream scholarship has come to recognise them as important, and often independent, historical sources, with many characteristics of being collated from various eye-witness testimony.
This is very different from the Quran’s account of Mohammad’s flight to heaven. Quite apart from the problems revealed by subjecting it to the same historical tools used on the NT, it was only ever represented as the prophet’s visionary account of his own journey, relayed to his followers. There is no history to be done on such an account, except on the matter of how and when the Quran came to be written.
In contrast, if (as we seem all to agree now) belief in the physical resurrection of Jesus appears in the earliest levels of Christianity, then the eye-witness claims of the gospel were subject, equally early, to refutation by the many enemies of the new movement, and it is unclear how it ever spread beyond Jerusalem, let alone to the ends of the Roman Empire within 3 decades, if the resurrection was false.