You usually don't have to manually install a compiler and all the dependencies. If you want to build a package from source which has already been packaged by the distribution, it's usually quite easy to do so. For example, in Arch Linux you can run

yaourt -Sb git

and it will get the PKGBUILD file for the package and allow you to edit it before building so you can build a newer version or alter build flags. When building a package this way, it will also fetch all of the packages it depends on in order to build and run. You generally don't have to think about dependencies at all.

In Ubuntu/Debian and Fedora/CentOS it is several more commands, although there are probably scripts that do it in a single command. It's still a lot easier than manually hunting dependencies and figuring out how exactly to build a package.