It is improving performance for EVERYONE. They just published the stats for their own stack so people can compare.
And 3% is still a lot if you're looking at global Internet traffic.
Ex: Why does clicking on a location link in google search load a big slow SPA to display a list of "cards" instead of just having a maps/web link in the search results?
Presumably if Search did link to Google Maps, other geographic information systems would have to be represented, just like various streaming platforms are represented in the video tab.
Nobody has moved over to HTTP2 yet, let alone HTTP3.