HTTP/3 is everywhere but nowhere

I've not followed HTTP/3 adoption and this article pointed out how it was both more adopted than I thought and less.

This is one example of the difference in fundamental pressures of the two tiers of organizations on the web here: open-source tools can't break things like this, and the libraries available to the long-tail are fragmented and uncoordinated. Meanwhile hyperscalers can make decisions quickly and near-unilaterally to set up implementations that work for their environments today, allowing them to get the benefits of new technologies without worrying too much about the state of the open-source common ecosystem for everybody else.

It would surprise me if open source doesn't get there, but how long will it take? It also highlights how significantly HTTP/3 breaks from prior versions, making incremental software adaptation more difficult.