I reckon that site owners would greatly appreciate being told when their host (not themselves in most cases) has not updated their system software, be it PHP or system libraries on which PHP depends. Most currently have no clue that they are running on a platform that has not been receiving security and bug fixes. At a minimum, WordPress should be warning site owners that their site is running (limping?) on an unsupported version of PHP and as such is at risk of being hacked.

I recently encountered a site owner who had a problem with one of my plugins. On inspection, I discovered that the site was still running PHP 5.3 (not the issue) with PCRE 6.6 (very old!) and thus didn't handle the much beloved \K operator. That operator has been available since PCRE 7.2 in 2007. The punchline was that her host had told her that the server was well maintained and kept up-to-date! LOL!

She was not best pleased to hear that her host was not keeping things up-to-date. I was not impressed much to discover that there are hosts pushing their old servers with no updates on unsuspecting site owners with the lie that they are new and current and shiny.

I reckon that WordPress has a duty to at least warn site owners that they are running on really old systems, and link to a page explaining what that means and what they could do about it. That's a minimum. Blah blah must still run on PHP 5.2 blah whatever sure, but at least let people know they are at risk because currently many don't even know.

Further to that, the About page has the opportunity on every WordPress update to promote the recommended version(s) of PHP and explain the benefits of upgrading. It could even explain why PHP 5.6 is still the recommended while PHP 7 could be better for their site. On sites running less than the recommended version, a bold notice could be displayed at the top of the About page warning site owners that they are not running a recommended version.

Sitting back and hoping that site owners will discover a page on a site they never visit is not going to help site owners. Most quite simply don't know to look, and trust their hosts to provide them with the best. Many hosts have not earned that trust.