[TheCoreh]

Just to clarify the meaning of the measurement, it doesn't mean they're 98% interoperable across everything, it's across the specific set of goals for 2025. (Which is still really good!)

I think they realized that shipping the features out of sync meant nobody could use them until all browsers adopted them, which took years, so now they coordinate

[lelandfe]

All of the above and even more so to have those features behave identically across the member browsers.