For a reader like myself, who read most of the company's output in the 1970s, there's no question that some sort of transition took place. From roughly 1970-75, Marvel Comics became far more experimental in terms of form and theme than had any other "mainstream" comics-company, with the usual exception of EC Comics. Some of this development was surely a direct consequence of the company expanding its line and therefore needing cheap young talents to fill the books. Not all of the young professionals who debuted in this time period were moved to experimentation, but for roughly five years Marvel Comics took on an aura of heterogenous creative expression. However, the Marvel "house style" had never completely vanished even during the most experimental period, and the late 1970s were by comparison a period of greater homogenization, even though Marvel's editors did still find outlets for developing new talents like Frank Miller and Bill Sienkiewicz.
Englehart's complaint, that the editors' desire for "the illusion of progress" interfered too much with the creative process, is one with which most fans can sympathize. Yet, even putting aside the alleged personal ambitions of those who tightened the reins, perhaps some pullback was inevitable.
In my essay on Umberto Eco's errors re: his comparison of myth-heroes and serial heroes, I said:
myth-heroes bear a strong resemblance to modern serial-heroes in that between the span of their births and deaths each hero has access to an infinitely-expanding "middle portion" of his life, in which he's always pretty much the same, with no commonplace causality to get in the way.
Eco talks further of how a reader must lose "the notion of temporal progression" when faced with a "massive bombardment of events which are no longer tied together by any strand of logic." Unintentionally he has defined the true status of archaic myth-narrative quite as much as that of the serial-hero. Indeed, in the wake of Marvel's soap-operatic twist on the superhero, it's possible to say that the myth-hero may at times possess less "temporal progression" than the serial hero.
There are narrative benefits to be had from preserving certain aspects of a status quo. Modern serial characters do not undergo a "massive bombardment of events" with no logical (i.e., "progressive") logic because the audience has been lulled into compliance with some Marxist commodity fetish. Such characters continually expand the "middle portions" of their lives because it's pleasing to audiences that the characters should be as the audience is not: functionally immortal and thus able to stand far more than the mere "thousand natural shocks/That flesh is heir to."
Elsewhere in the Eco essay I asserted that myth-heroes possessed what I considered "dominant" characteristics rather than the "immutable" ones Eco assigned to them. Dominant characteristics are important to any characters who appear in continuing stories; such characteristics define what expectations the audience should have for the character.
Ironically, many years later the sort of organic progress that Englehart and others advocated mutated into the phenomenon of the "event." Most of the time these events placed serial comics-characters through what I termed "earth-shattering changes at the last minute,", only to largely restore the status quo in the end. Jim Shooter's SECRET WARS series was perhaps most emblematic of this idea, although admittedly the "black Spider-Man costume" subplot spawned in SW did actually become an ongoing concern within the assorted Spider-books. But possibly the most peculiar "event" was one that initially seemed designed to oust the hero of the SPIDER-MAN title out of his own book: the infamous Spider-Clone saga of the 1990s.
In the "Earth-Shattering" essay, I mounted a measured defense of these type of events by noting that they depend on calling forth what Lee Drummond called "the elemental level of crisis," particularly though not exclusively for continuing characters. In terms of my own taste, I prefer the organic approach to progress to the more artificially-promoted "event" mode. At their best (if there any good ones!) event-stories are quick vacations from the status quo, like DC's Silver Age imaginary stories. But anything that can be done can be done badly, and often "event" stories, such as the 1990s Clone Saga, descend into fatuity by undermining the very concepts that make the series workable, as with the notion (later discarded) that the Peter Parker with whom the fans had identified for years was actually a clone of himself. Perhaps this notion would have borne some fruit in a satire, but as past of an ongoing adventure-series the idea was a bit of boneheaded incoherence.
Which may suggest that there's something to be said for homogenous creativity as well as the more experimental form. More on that later.