If you arn't using a IRC server with build it bouncer (like ergo.chat) you really need an additional bouncer (linke ZNC or Soju) with an IRC network. As you say this is not an optional feature, but a must have. Most traditional IRC users run their own bouncers, so they feel no need for large networks to implement this vital feature and thus hold back IRC as a whole.

That said, if you had provided a nice client with built in bouncer and multimedia functionality, like The Lounge or Convos, or used an external service like IRCcloud, I doubt you would have had much issues with IRC adoption in your team. The Lounge especially also works really well on mobile.