If WP is moving through PHP versions and performance... why are so many hosting providers that still have notices for us not to update into WP5.0?

My point is... if PHP version is correct, plugins and everything seems WP5 compatible... Is there anything else I am missing? Or with this performance improvements even the worst servers are capable to run WP without any issues?

I know this is more a hosting-related issue, but I am confused with WP going through and hostings (at least mine) staying back.