It matters in the “I stumbled into this public chat room” sense. It doesn’t matter in the “we need a private comms channel” sense.

At the end of the day, the point is that XMPP was never trying to “win” against IRC, ICQ, AIM, Matrix, et al.

Market share only matters if there's a market, ie concurrent proposals. In an open world, concurrent proposals make no sense: let all applications talk with any other, let all protocols take inspiration from each other to build the best infrastructure.

There's nobody to talk to because companies explicitly make it so, not because a protocol is better than another