The gatekeepers (telecoms) first decided they were going to publish things themselves too, which had zero success, then to pay themselves more than anyone on the platform, then when that still didn't work they kicked everyone else off the platform with various excuses (porn, crime, getting money from outside the platform, promoting non-sanctioned shows, ... the big thing that was successful were mail and chatrooms)
The problem is that these companies were always willing (after a short while) to damage the economics of the infrastructure as a whole, just to increase their own share (for example per-email charges). Eventually they had close to 100% ... of nothing.
And the irony is that because of these companies constantly trying to move into content and apps, destroying their own system more and more by crude attempts to force people into their content the only thing that remains of these systems ... is publishers. They couldn't really improve their apps, since that cost them money. They quickly discovered to use money as a way to avoid friction on their apps ... and then no business leader ever approved removing friction anywhere.
For example: https://en.wikipedia.org/wiki/Minitel https://en.wikipedia.org/wiki/AOL
