You're right here for sure. But the bonus is that Doug in accounting
will be able to use his crusty old projector without dongles

It's not just old projectors though, it's also new TVs / monitors, which is a huge bonus - jury is still out on how well Apple Silicon Macs will support Windows gaming etc going forward, but if they do at some point, this could be a decent bonus.
I'm not sure on whether they'll ditch HDMI as soon as USB / TB support 80Gbps. I really think the rumoured Apple monitor will include an HDMI 2.1 port, which massively opens up the potential audience for that display too, beyond just Mac customers. If that's the case, you'd hope Apple would continue to include HDMI 2.1 and beyond for a while yet.