The issue is that those previous promises were for a very short support window

Not really. The previous phones already had a way longer support window than almost any other Android phones on the market, which mostly only get a year or so of updates. It's a defining feature of pixel phones.

Google has a great track record at fulfilling its promises of support, but a terrible track record of giving un-promised support. So when they promise support, that should go into the "good track record" column.