The weight of backward compatibility on php libraries

[ThanogHamros]

Updating PHP libraries to remain compatible with older versions is becoming more and more difficult. Although backward compatibility is necessary, effort is being hampered by the widespread support for PHP 7.0 and even 5. Libraries are forced to give up on type safety and current features because of this over-reliance on outdated PHP versions.

It's time to reevaluate how much to give older systems support while utilizing the latest PHP features. Maintainers of libraries might be encouraged to concentrate on contemporary development techniques if there was a clear end-of-life plan for previous PHP versions.

What do you think would be a fair PHP version omeglz online2yu threshold for library support?