Publish Online feels stagnant

Adobe has explored this space with prior efforts, all of which are obsolete (as far as I know).

As much as I respect Adobe for trying to create a solid publishing platform in the cloud, more or less, I think the concept presents issues and probems too big even for them. A successful (== widely used and enduring) solution will be, for one thing, open-source and not locked to one production or presentation format, and certainly not to the indirect need for paid service accounts. I think PO has reached some hard limits, some of which greatly resemble having painted itself into a corner.

But that said, it's another example of how baffling it is that a platform approaching its 40th anniversary (HTML) remains fragmented and increasingly difficult in which to achieve consistent advances. (I blame the extremely stubborn "fluid forever!" faction for this, but maybe that's just me.)

Use Publish Online for what it is and take any advances or extensions as gifts. And a word of warning repeated all too often here: Don't make it a core element of a client or paying service!