There is no reason for a tool to implicitly access my mounted cloud drive directory and browser cookies data.
Linux people are very resistant to this, but the future is going to be sandboxed iOS style apps. Not because OS vendors want to control what apps do, but because users do. If the FOSS community continues to ignore proper security sandboxing and distribution of end user applications, then it will just end up entirely centralised in one of the big tech companies, as it already is on iOS and macOS by Apple.
So when it's all said and done, I do not expect practical levels of actual isolation to be that great.
The data doesn't support the suggestion that this is happening on any mass scale. When Apple made app tracking opt-in rather than opt-out in iOS 14 ("App Tracking Transparency"), 80-90% of users refused to give consent.
It does happen more when users are tricked (dare I say unlawfully defrauded?) into accepting, such as when installing Windows, when launching Edge for the first time, etc. This is why externally-imposed sandboxing is a superior model to Zuck's pinky promises.