Major update, awesome. /s
As someone who manages a network of 250+ WordPress websites - these PHP updates are killing me! As soon as I'm done helping clients upgrade/fix their incompatible themes/plugins and custom code, a new version is out! Even with great tools, the process for about 10% of my network is a nightmare.
While I appreciate the work, it's not very satisfying and for many clients very frustrating to pay for something they know nothing about, just to "keep the lights on".
That said there are languages where very little backward incompatible changes are made. Java comes to mind.
Also: putting each client in a sandbox (VM, VPS, etc) can help you to keep some clients on the old versions, and/or do PHP interpreter migrations on your own timeline.
I do and appreciate the job security but I respect my clients (small biz owners) and it's just not satisfying and for the 10% that have issues, costly.