"Most" maybe by count, but I'm not sure if it's "most" by usage frequency. There have been & will be lots of nonsensical deprecations that are much more common in existing code than "putting volatile on an object argument" (which I've honestly never even seen anyone do in my life)... like static (which was undeprecated, thankfully, but how were people supposed to know this ahead of time?), std::aligned_storage, std::bind1st, std::iterator. They're frustrating as heck, have questionable merits to begin with, and working around the deprecations in existing code provides practically zero business value.