When Matthew Rosenberg writes on Twitter (2, 3) that writers share some responsibility to promote an upcoming work, he accurately describes the reality of launching a new comic into 2019's retail landscape. He does not absolve publishers of the responsibility to promote the work at all.
This isn't a big enough or healthy enough industry to absolve anyone of doing the work needed to support all parts of it. It's an ecosystem and everyone should be contributing however they feel they can.
Actors who work smaller theater productions set up chairs and take tickets. Bands in small clubs help set up and take down each other's gear, work the door, sell tickets. Directors on low budget films carry gear, help strike sets. Why should comics be different?
Only focussing on the aspect of the job that you want is nice, but it's not a luxury comics often provides. Promote comic shops. Promote comics press. Promote your fellow creators. Support every part of the comics ecosystem and they will support you.
Remember Kelly Sue DeConnick's fantastically successful Captain Marvel relaunch? The one with the great Jamie McKelvie redesign? That didn't come courtesy of Marvel, that came courtesy of DeConnick commissioning a McKelvie redesign with her own money. She hustled to promote the comic before issue one ever became known and that was five years ago. Hell, that doesn't count the pins she made on her own dime and time to send to retailers to give out with a purchase of her relaunch's early issues.
That's what Rosenberg means. Not that any publisher's PR department can play FarmVille from 9-5 while the authors beg for magazine interviews. He means that standing out on a month to month basis means the team must grind publicity in their off hours in addition to creating the comic from whole cloth.
This obviously sucks. I'd prefer the authors spend their time making the comic and get weekends to rest, rather than feeling correctly they need hang out their shingle every two weeks at a con (or every day on Twitter) just to keep a work for hire gig from an impending relaunch. Hell, Warren Ellis has to beg his own mailing list to buy Trees: Three Fates. DeConnick is currently out on Instagram hawking her new Aquaman issues (maybe you heard of last year's movie headlined by Jason Momoa's abs?), Bitch Planet paraphernalia and the upcoming Pretty Deadly: The Rat.
Finally, Jude, between you, me, and the reader: If Matt ("Is There A Printing Of 4 Kids Walk Into A Bank #1 Who'se Proceeds I Haven't Donated To Charity") Rosenberg is your corporate stooge, we're in a real good spot for stooges.