The only aspect of that characterization I'd agree with is that the Spider-Man movies had more Stark than I'd expect, but we'd had five completely MCU-adjacent Spider-Man movies in the past decade, so Marvel kind of *had* to do something very different than a *third* retelling of Peter's origin.
But the other non-Avengers movies, Guardians, Dr. Strange and Ant-Man could as easily not been in the MCU at all as much as Cap and Tony mattered to the plots. And since two of the three already have sequels, and the Dr. Strange sequel is on the way, they seem more like successful chapters in the franchise, not 'filler.'