The tricky part of this is that if your project is a library, you're not just opting into having to update your own toolchain, but also that of all your users. This means that a lot of library developers will err on the side of not updating their minimum version, which in turn means application developers don't have as much pressure to update either. This isn't specific to C++ by any means, but I think it does pop up a bit more in this space due to the fact that a lot of developers prefer to just use the default toolchain of their system, so forcing downstream users to update their toolchain could be viewed as a bit more of a maintenance burden.