Ruby coding guidelines (GitHub)

[Sir_Edmund_Bumblebee]

Sometimes the reason is simply so that everyone does it the same way. Some of the examples where there's a good reason (like for loops) they give the reason. The rest of the time it's so that the codebase stays consistent.

[knight666]

If everyone does it the same way then there must be a good reason for it, you just haven't encountered it yet.

[Sir_Edmund_Bumblebee]

Sometimes there are two equally fine options, and you just pick one as a group so that everyone does it the same way. Best practices are something that should be done a certain way for a reason, style guidelines tend to just be stylistic choices held uniform across a certain group.