Actually, I misunderstood your question there because it’s true - you can use trackPageView to add a custom page title (just like you did there). You can use the method I mentioned in case you want to overwrite every event before the page reloads. Sorry for the mix-up.
why it’s not possible to trigger by page title
I think it’s just a missing feature, I’ll add a feature request for this. For now, it’s best to create a custom variable in the Tag Manager like I describe here. You’ll be able to add the variable in the trigger conditions.