Why do you think working with a group of people on a C codebase introduces pain unlike other languages? Working with a group of people always causes pain, but I found the pain much less severe for C than for C++.
In my mind using a simpler language should be less painful given there is less to argue about given syntax and versions etc. Take c# for example you have multiple ways to do the same sort of things.
Your question also hides an answer. You don't often get to chose a group of people you work with, and unlike projects that self-attract and self-distill ideal profile (like linux mentioned in sister comment), you're left with people usually not used to ye olde C idioms. With C++ it's a bit easier since it is more widespread and supports some of the idioms people get used through schools and other projects. Of course, projects (should) always dictate a certain discipline by different mechanisms, but if certain way of thinking isn't ingrained then it introduces just that much more pain to the communication layer between people.