Yes, there are certain tools that I trust almost completely, like TeX [1], and it helps me focus on finding my own bugs because I'm not tempted to spend some time wondering if is the tool (build tools, library, compiler, etc.) with the bug and not my own code.
But once you start to use LaTeX you are not long so safe. If you use two LaTeX packages, you have to pray that they are compatible, and they are loaded in the right order. If you have to use babel (because you don't speak in english) you are probably out of luck.
You are so right! (I blame the macro expansion based semantics of TeX packages.)
I end up using a small number of very large packages that do almost everything I need instead of trying to get numerous more focused packages to work together. (Memoir or KOMA, and TikZ handle most of my tasks.)
[1] http://texdoc.net/texmf-dist/doc/generic/knuth/errata/errorl...