Here is a good article (sorry i'ts 2 pages too late) about how publishers make money even though many authors don't earn out their advance:
https://stevelaube.com/the-myth-of-the-unearned-advance/
I strongly suspect that the myth of the publishers who do nothing and force their authors to market/have vast platforms, comes from a select group of people within the indie author community (
NB: I'm not grouping all indies into this category, just a handful of evangelists.)
In practically every writer group I'm in, anytime someone asks about trade publishing they get immediately jumped by a couple of big gun indies who promptly inform them that trade publishing isn't worth pursuing because you can't attract an agent or a publisher unless you are already an award winning short story writer or unless you have a huge Twitter following, that agents in particular never take on debut authors. Agents and publishers are out to take away your creative control, there's always a risk that they'll simply nick your work and publish it themselves.
And then, even if you do get trade published, you'll be forced to do all your own marketing whilst having no creative control, no support, and less income because they will stifle your earnings and take too big a cut.
It's a shame because that kind of a statement makes the indie vs trade discussions absolutely impossible to have. I would love it if newbies could get a balanced perspective on what is right *for them* (and for some, it IS self publishing) but this never happens; and attempting to counter any of the points sounds argumentative/defensive by default.
The main advantage of trade publishing (at least, the main one for me) is dismissed as a mirage of lies, and becomes very difficult to counter because people *want* to believe the system is rigged against them. And so it spreads.