> At least if folks use something like Symfony or Laravel it's harder for them to shoot their foot off
I'd like to consider giving Symfony or Laravel a try, but at work we run Debian and stay with a given release until it is near the end of extended long term support.
Laravel's oldest release that is still supported is 5.5 LTS, which requires PHP >= 7.0.0. The next oldest still supported is 6 LTS, requiring at least 7.2.0.
We're on Debian 8, Jessie, which is on extended long term support until 2022. It has PHP 5.6.29, so no Laravel for us. Even if we were on 9, Stretch, which has PHP 7.0 and so could use Laravel 5.5 now, Stretch is on long term support until 2022 and will be on extended LTS for probably a couple years after that, we'd run past Laravel's LTS.
Heck, even if we were on the current Debian, which is 10, Buster, which has PHP 7.3, it is not clear we could use Laravel. Laravel only does security fixes for 3 years on LTS releases. Buster has Debian support until 2024, LTS for a couple years after that, and then extended LTS for a couple year, so it will be past the end of security patches for the current Laravel before it even reaches LTS.
So unless I can be sure that the next LTS release of Laravel does not raise the PHP requirement past 7.3, Laravel is out of the running.
(But wait...what about https://packages.sury.org/php/ which is a package repository maintained by one of the main Debian PHP packagers where he packages newer PHP for older Debian? That's close enough to the official packages that I could probably convince the IT folk to add it. Alas, he only packages for older Debian until they go out of LTS. If you stick with it through extended LTS, you are out of luck).
With Symfony, 3.4 is the oldest supported release. That requires at least PHP 5.5.9, so will work on Jessie or later. However, 3.4 support ends in a couple months. That will leave all supported Symfony requiring at least 7.1.3 which means you have to be on Buster. It looks like they have a similarly short LTS support life as Laravel, so even if you are on Buster today, there doesn't seem to be any good reason to believe that there will still be a supported Symfony that works there at the end of its regular support lifetime, let alone that one that can take you into Buster's LTS or extended LTS.
Debian is the only Linux distribution for which I've looked at this in detail, but a brief look at others suggests that the situation is similar for Red Hat, and maybe Ubuntu.