The browser was not started with the idea of taking over the main focus of development, it was just another part of an already pretty large hobby OS project
Fine. With decades and decades of memory safety lessons in the books, it's hard to imagine how C++ was the language of choice when starting new operating system from scratch in 2018.
It really isn't that hard to imagine someone starting a fun hobby project in the language they enjoyed and were the most comfortable with.
Dunno. It really is. Debugging memory corruption bugs in complex one-memory-space systems is very much not fun.
Nothing a little printf (or dbgln as it is known as in Serenity-Ladybird land) can't fix