The real concern here is that if Google dumps a proposed standard out there, and ships it broadly in Chrome by default (as they have for other standards they’ve wanted to push), then it will quickly become a de-facto standard and force its way into the standards regardless of how severe the problems with it might be.
We’ve seen how well that worked out in the past with stuff like touch events and Shadow DOM v0, and we don’t need to repeat that with “toast”, so it’s hardly surprising that folks get twitchy when they see Google doing something which indicates we will repeat that past yet again even more intensely with many multiple features (here’s looking at you, Project Fugu).
These days Google honestly seems more interested in shoving whatever they and a few other large companies want out into the web platform as quickly as possible in an 80% done form (if that), and then waiting for everyone else to do the really hard 20% of the work of de-Blinking and properly standardizing it over many months, while Google gets to act like heroes for “moving the web forward”.
Things wouldn’t be so scary if they never pushed out their draft implementations for broad public use until there was at least one other generally-interoperable implementation. But even if they have great individuals working for them who want that to be true, they’ve organizationally decided to be bullies instead, right down to how much of their own web services are “best in Chrome” (and almost never because Chrome is best, but because they design to Blink’s quirks and quirks of their draft spec implementations first, then maybe some day make a truly standards-compliant version).