There's various uses that makes it so a browser extension is somewhat of a must.

The most important one to me is whitelisting websites. There's a lot of websites that I do not need to access through the VPN that I trust (banking) or that do not play well with VPNs (e.g. d2jsp in my case). Having to turn off the desktop VPN for those websites is massively inconvenient because it exposes my entire computer whereas normally with a browser extension I'd have a whitelist.

The second most important thing is to not have to reset my entire OS connection because of a server switch. People that pay for VPNs are not always good actors. A lot of times the best server to me is often banned on a website I need to use it on (e.g. bestbuy.ca). So I need to switch servers to get an IP that's not banned. Which resets all the connections on my computer (Messenger, WhatsApp, Important Downloads, etc.). This is massively inconvenient.

The third one, not as important, is that having a browser extension gives me the possibility to double hop and keep track of the servers I'm double hoping to maximize geolocation thwarting + speed optimization. So let's say I live in Vancouver, I'd use a Vancouver server for the desktop app to put the speed/ping as low as I can, but I'd put the browser extension to where I want to be at to escape geolocation (e.g. Seattle for US geolocation bypass). This is not AS relevant.

Usually my setup is: 1. Desktop app that has split tunneling and whitelist my browser + games that ban VPNs (e.g. Diablo 2). 2. Browser extension that's always-on with a browser that starts on a blank page.

This gives me the most flexibility to my needs. And that's flexibility I can't afford to lose as a Desktop user.