Browser extension doesn't help any scammer to steal your money. This news could be fake news to downtrend of browser. Why Top popular browser do it, when this apps has trusted users. Especially Google doesn't want to vanish own logo trust which they gained after long fight. I heard that Google and Mozilla already removed some fake extension from their browser.
There is a contradiction since you said fake extension are removed by Mozilla and google, that means the scammers were able to add fake extension and the browser needed to remove them after identifying them to be fake, if you are storing your coins make sure you keep that in a external device which is not connected to the internet.
it's very vulnerable if the wallet is kept online, it's better to store digital assets can use nano ledger, or trezor to store digital assets because in my opinion it's safer than saving it in a browser extension, I also use nano ledger as a storage for my assets
I personally don't suggest having a wallet on a browser adds on. Most of us know that it is very dangerous especially if you are downloading everything on the internet. Virus on a computer isn't new, But the way of penetrating into your own computer is changing and some way of the hackers do is penetrating through your browser. Imagine if you have your wallet into your browser, I can't really be sure if you can protect it right there. Using hardware wallets is the safest bet to protect your assets.