I used browserstack you have to make sure page shows correctly in different browsers and devices.
To me that's more important than some of the tests ran in laravel simply because you can test in real life and either it works correctly or don't work correctly, where as browsers there are many differences.
I had one situation where a certain image would show correctly in the majority but in one particular device it showed sideways so this sort of thing has to be corrected.
Unless of course it's a business app and you tell your users the choice of browsers they have to choose from.
However an application such as this forum you probably have to test on a variety of browsers.
I've never been worried about every browser but at least most used ones I made sure apps work.