That's true, there is not even Chrome & Firefox browser, surprisingly.
UC browser and Opera mini are there, but the UI and features are very simple. Even WhatsApp is so different and dull in dark theme.
Internet Explorer and Microsoft Edge remain the only suitable choices for web browsing, which are sufficient for web browsing. Built in Data Sense is very helpful feature for mobile data users with limited bandwidth.
Windows 10 mobile and Project Astoria will hopefully fill this app gap, otherwise no hope for Windows Phone survival with this much app gap.
In Windows store, one may not be able to find his favourite app for some specific task, but there is always some alternatives out there for many things. So this atleast helps.