Would they disagree, new toolchains work great with old code? And even add 95% of the features to older editions, just not new keywords or inference defaults. I think in C++ people complain about the effort to migrate --std, rather than having to learn variants or concepts. It does add to the complexity of course, and it's useful to agree on a consistent style, I just mean Rust doesn't have the particular issues with everyone having to migrate in lockstep, or anyone needing to for new tools