If Signal was the only alternative to have an internal messaging tool, sure, it would make sense to invest time and money on it to keep it up.
But it doesn't. There are options. If I had to choose, I would rather invest this time and money to collaborate on the existing protocols that do have the goal of being fully open. Matrix and XMPP can do the things that I want and there are plenty of people working on them to overcome the present issues and challenges for mass adoption.
Why should I swim upstream by myself if there is no special reward for this kind of effort?
