it was obviously marketing material, but if this tweet is right, then it was just blatant false advertising.
The eventual removal of that tier and anything even close speaks to Google's general issues with cancelling services, but that doesn't mean it was less real while it existed.
I don't remember the "increasing forever" ever being particularly fast. I found some results from 2007 and 2012 both saying it was 4 bytes per second, <130MB per year.
So it's true that the number hasn't increased in ten years, but that last increase was +5GB all by itself. They've done a reasonable job of keeping up.
Arguably they should have kept adding a gigabyte each year, based on the intermittent boosts they were giving, but by that metric they're only about 5GB behind.