For those who don’t know what the hell is Matrix:

Matrix defines a set of open APIs for decentralised communication, suitable for securely publishing, persisting and subscribing to data over a global open federation of servers with no single point of control. Uses include Instant Messaging (IM), Voice over IP (VoIP) signalling, Internet of Things (IoT) communication, and bridging together existing communication silos - providing the basis of a new open real-time communication ecosystem.

Technically, you’re correct.

However, many websites doesn’t follow the appropriate HTML standards and just abuse h1 and p.

I just tried it with Google.com and it seems to remove all html notations other than text.

It useful in some cases such as wordpress one-page websites which have their story, mission, products, etc…

I don’t think all websites supports read mode.