ON A SIMILAR AND EQUALLY IMPORTANT TOPIC: Big tech isn't blocking Matrix adoption or XMPP. Maybe when they're a bit older, but they're not currently scalable or robust enough to take on proprietary solutions.

Actually, they did. Back in the day all the big companies were using XMPP. For a short time it was glorious. And then little by little they started closing it off and/or making it incompatible until they stopped using it altogether.