> is not up to the task of improving algorithms for email server reputation? No, they are definitely capable of improvement. It's simply not of interest to them.
Incorrect, if they stopped spending all that money and effort to keep up, their users would get flooded.
> Of course anything can be gamed
Sending spam/marketing e-mails is a multi-million industry. Both on illegal and legal markets. It's a constant race.
Google--a technology giant with algorithms and heuristics running most operations--is not up to the task of improving algorithms for email server reputation? No, they are definitely capable of improvement. It's simply not of interest to them.
I can hardly blame them because the cost-benefit analysis clearly says, "why bother?"
Of course anything can be gamed, but magnitude matters. I've had the same domain for 24 years, with many hundreds or thousands of email conversations between users of my server and those of the major email players over the years. I had to switch my mail server's IP address two years ago. Immediate zero reputation from many big players.