It seems that the author never heard of AirMessage Signald, Whatsapp Business API, Beeper or any of the malware infested clients for end to end encrypted chat apps.
Bridging is already happening today, the best we can do is ensure it happens in as secure a manner as possible, which is much more difficult when a closed platform is actively hostile to bridge users.
Good. The per-device message encryption UI/UX is one of the main reasons matrix/element sucks to use. Is it valuable? I'm almost certain. Is it a huge blocker for the average user? Yes.