Yes, and so are they. The only reason they don’t upgrade as quickly as they could do is because of unnecessary and frivolous BC breaks. If you look at http://w3techs.com/technologies/details/pl-php/5/all you will see the following for PHP usage:
- 19.5% of sites are still on version 5.2
- 45.5% of sites are still on version 5.3
That means that 65% of PHP users are at least 3 releases behind. Is this an issue or not? And what causing this situation? Why, breaks in BC of course.