I do this. I self-host rather than use Beeper but the effect is the same. Single client (Element) to my own Matrix server (Synapse) with bridges to WhatsApp, Signal, Telegram and Slack.
Back in the 90s I hoped that being online would raise everyone's game and we'd all become more technical, in general, and adapt. Sometimes, now, it feels the opposite.
... or just publish the source on Github and let someone else continue the legacy.