Google is an ad company. They're not a browser company.
The same technology could easily be applied to simply blocking anyone who isn't verified (in the name of stopping spam, DDoS, bank security, you name it), meaning anyone not using an approved install of Windows/macOS/Android/iOS is shut out from the internet.
In the long term, in the name of "banking security", they're likely to add a mode that also lets you ensure your pages aren't tampered with by extensions, and there go all the ad blockers.
Reddit wanted to control how users consumed content on their site. To control the experience (i.e. monetize with ads), they had to shut down third-party clients, since those could remove ads.
Google appears to be doing the same thing, but for the entire web. WEI is a way for sites that want to monetize with Google ads to prevent folks from accessing their site unless they can cryptographically assure that the user's browser will follow all the rules Google sets. We don't yet know exactly what all those rules will be, but it isn't hard to guess that they'll be along the lines of whatever makes Google the most money.
This applies to desktop browsers, but also affects automated tools like wget and curl. It could kill web scraping altogether.
Sounds like a great way to enforce censorship:
- websites can deny access to unverified web browsers / web clients
- WEI-enforcing web browsers / web clients can refuse to go to unverified websites (not a stated goal, but it is a logical next step to boost website adoption of WEI APIs once a critical mass of clients is reached)
Google wants to build a wall around the Web and have their own walled garden:
The problem was that if you used a third-party client, Reddit would have to coordinate with them to launch whatever new stupid cryptocurrency scam they wanted to push that week. On a web browser they can just push new code into it[0], and their first-party mobile clients can be updated ahead-of-time with support for the feature. But third-party clients would have to spend their own development time adding stupid "click here to get your Snoovatar[1]" links. They could slow-walk that, or just not implement that, and Reddit would have to spend time and money kicking users off that third-party app.
This, incidentally, is why every other major social media platform bans third-party clients. Third-party clients are user agents, not platform agents.
[0] Which, incidentally, makes web browsers not user agents
[1] An NFT scam Reddit tried to pull
That one is in the category of things that is little more than a nuisance in practice since it’s so easy to circumvent, but that’s a hardware thing and therefore it’s easier to plug something in that is unauthorized. Things are getting so tightened up on the software side with secure boot, Apple’s read-only system partition and by-default App Store Only policy on the Mac, etc. that I suspect this type of thing will be a pain for normal people, though actual at-scale bad actors will probably figure it out.
Whatever someone may think of Google or even of ads, it’s smart to keep that important thing in mind and remember their alignment is and must always be toward maximizing and improving advertising.