Sorry for another necro but I want to thank zfn for finding this amazing fix.
also noting that it seems you can have it both ways if you just make two shortcuts. Make one with the launch options and one without, and then just change the name/icon of each shortcut to denote which is which. To close steam via desktop you'll have to close it from the first shortcut you made though. You'll have to restart steam to get the desired webhelper setting each time but I found it highly worth it imo. guessing there could be another way around it but this is what I've been using so I figured I'd mention it. you can also use firefox or another browser ofc too. thanks zfn!!