Most users don't need that level of power or customization and it just opens up not only attack vectors but general UX confusion. Hide that sort of thing behind an admin mode or whatever, but otherwise, yes, PLEASE hide dangerous functionality so people aren't exposed to them.
Users aren't asking to be treated like children, they just don't want to have to think about zero-days and layers of config menus because some developer in an ivory tower valued "muh freedoms" too much.
The basic point of my comment is that deprecating the capabilities or the current API just because there can be a security risk in some cases for the average user is harmful to the more advanced users.
You focus on one possible solution mentioned about warning dialogs. However, there are lots of different solutions available which would allow it to run only with knowing 100% that the user knows what they're doing aside from warnings.
There can be a command line flag --developer etc. just like there is for unsafe certs.
'Use a browser that supports it' is not a solution since - as you said - Chrome has the largest user base why would a developer put in the effort to develop a solution for a minorly used browser.
Since the major browser is closing this API there will be no possible use of this type of functionality for anyone - even the users who know what they're doing.
Wonder how long that'll be an option. I use FF for all my browsing and its amazing how much stuff breaks if you're not using chrome. I'm thinking the re-captcha stuff should be used as evidence in a google anti-trust case :-P "Oh, your on firefox? here...lets identify all these pictures.."
I wish I still had that kind of innocence.
Malicious extensions are probably the biggest existential threat to the web as a platform. If browser regain the reputation for being insecure that they deservedly had 15 years ago, more and more serious business will move into mobile app walled gardens. This has to be solved.
But rather than accept the simple explanation, we get these inane conspiracy theories on what the true motivation is. No, it's not about ad blockers because the subject of this blog post is not a feature that ad blockers would use. And the same for the half dozen alternative explanations.
Seriously, what is wrong with you people? Can't you at least save the high school level cynicism for situations where an assumption of malice makes some sense?
Got any stats on what percentage of the browser install base has even one extension installed? Then we can come back to your "tHe biGgEsT eXisTenTiAL ThReAt" nonsense.
And how an assumption of malice doesn't make sense when we're talking about the world's biggest ad company doing something in the name of security that happens to cripple ad blockers -- well, suffice to say, you're probably not cut out for journalism.
Now go get some rest?
The people who need this functionality are a very small minority. Tampermonkey has 10M installs which is phenomenal, but Chrome apparently has an estimated 2.5B active users. The tradeoff here is exposing billions of users to unnecessary risk, to save two orders of magnitude fewer of the most tech savvy users from an insignificant annoyance. I.e. just use a browser that supports the extensions you need instead.