I'm glad I read Starlin's WARLOCK run as back issues, because I never would have been able to follow it when it was coming out. First the material that preceded Starlin was very random and all over the place.

The Warlock character debuted as "Him", an experimentally bred human-like creature whose scientist creators didn't give him a name, by Lee and Kirby in FANTASTIC FOUR 66 and 67 (Sept and Oct 1967).
Then a follow-up appearance in THOR 165 and 166 (June and July 1969), also Lee/Kirby.
I think he officially became Warlock in MARVEL PREMIERE 1 and 2, by Thomas and Gil Kane (April and May 1972).
Followed by a WARLOCK series 1-8 in his own title, with a disjointed merry-go-round of different writers including Roy Thomas, Mike Friedrich, and Ron Goulart. And artists Gil Kane, John Buscema, and Bob Brown, and the only consistency across its 8 issues was all were inked by Tom Sutton (bi-monthly, from Aug 1972 till Oct 1973).

Then what few people probably even know about, Warlock orphaned from his own title made a guest appearance across INCREDIBLE HULK 176-178 (June, July, August 1974) in a 3-part story by Thomas/Conway, with art by Trimpe/Abel.

Then Starlin got a shot at the character, revived in STRANGE TALES 178-181 (Feb 1975-Aug 1975). Which apparently was popular enough to revive the WARLOCK title in WARLOCK 9-15 (Oct 1975-Nov 1976) before apparently being unpopular enough to be cancelled again!

And while the series didn't miss a beat in its bimonthly schedule from STRANGE TALES 181 to WARLOCK 9, it wasn't at all clear in 181 that it would be continuing in WARLOCK 9. I could picture a lot of readers picking up STRANGE TALES 182 with Millie the Model (I'm joking, it was a Lee/Ditko Doctor Strange reprint), thinking the series ended there. Starlin probably lost a big chunk of readers who thought the series was cancelled mid-story, unless they were lucky enough to see WARLOCK 9.

And in any case the series was cancelled anyway with WARLOCK 15 (Nov 1976).

With a random Warlock appearance by Mantlo and Byrne in MARVEL TEAM-UP 55 (March 1977).

And then again, only by being very lucky or through psychic osmosis would you know that the WARLOCK series was concluded by Starlin in a 2-part story across AVENGERS ANNUAL 7 and MARVEL 2-IN-ONE ANNUAL 2 sometime in the summer/fall of 1977.

So... it was far easier to buy and read the complete series as back issues and collected form much later, than it was when it came out.

I saw the WARLOCK issues on the stands but as a 12-year-old it didn't interest me and I didn't buy them, probably partly because I would have been walking in mid story, with no easy access to back issues then.
I first read the Starlin WARLOCK stories as backups in FANTASY MASTERPIECES (backup to Lee/Buscema SILVER SURFER reprints), which again got cancelled before the reprint was concluded! So I sought out the back issues at that point in 1980-1981. A comic shop owner guided me to AVENGERS ANNUAL 7, that I thought was the conclusion.
A year or so later a Marvel zombie friend let me know about MARVEL TWO IN ONE ANNUAL 2.

And not even a year later, Marvel released WARLOCK SPECIAL EDITION 1-6 reprinting the entire series in a much nicer format.

And then 10 years later (1990) Marvel reprinted it again in a second 6-issue reprint series. I don't know exactly when someone had the brilliant idea to reprint the whole series in collected book form (although for some reason, they deleted the Byrne story from the trade, possibly from the Masterworks hardcover too.)

So you young pups have no idea how much easier it is to read this stuff now! I had to walk 20 miles each way in the snow to buy these issues! And even then, it took me years to complete the run. Although quite honestly, the chase of seeking out and finally getting these issues and other 60's/70's material was actually kind of fun, even if a prolonged adventure.