But it is popular! YouTube's preferred format uses opus for most, if not all, videos upload in the last ~5 years (they also offer an AAC option alongside it). Several VoIP services use opus, including Zoom, Discord, FB Messenger, and WhatsApp (until recently). Opus is part of WebRTC and thus implicitly available for audio/video conferencing software that runs in the browser. And if you look up what audio enthusiasts recommend you use to encode your lossless music for smaller file sizes, it's almost always opus!