Regular browsing - in my opinion - should default to privacy and security first, whereas trust to web apps should be granted on a per-domain basis. This is basically what I'm doing in a crappy manner in Chromium and Firefox, where I have all my Browser Extensions in regular browsing mode with uBlock Origin, Cookie Autodelete and whatnot... and where I use Incognito Mode to use Web Apps.
Additionally, I believe that a Web Browser that's decentralized has an almost infinite amount of advantages when it comes to bypassing censorship, increasing trust and the ledging aspect of (temporary) online resources.
My idea of building a sane architecture of a Web Browser is that the Browser itself is actually a locally running peer-to-peer web scraper service, and the "frontend or GUI" is a bundled webview that's pointing to localhost:someport. Web Apps can then be used by spawning a new webview instance that's sandboxed with its profile in a temporary folder, so it cannot infect/spread across the regular profile folder that's being used for the "regular private browsing" mode.
This architecture allows all kinds of benefits, as everything can be filtered, cleaned, verified (, and shared with other peers) at the network level before it reaches the webview - whereas Browser Extensions currently cannot filter any HTTP responses because there's no API for that.
AdBlockers currently are based on a disallow-list based concept, which means the advantage is always on the advertising side, and by default nothing is filtered; and scammers/blackhats have always the advantage. Once you add it to a filter list, lots of people's machines have been compromised already. But what if AdBlockers change instead to an allow-list based concept - meaning that the Browser maintains a list of resources that are allowed to load per-domain, and the default being just text and images?
If you want to take a look at where it's at right now [1] [2], my Browser is open source; and I hope to fund development via a access fees for a peer-to-peer "Knowledge Tracker" that allows to share automations for the web with other peers, aka macros, reader-mode like extraction beacons, and other awesome treats (p2p search and recommendations are basically included in this concept).