PHP team has always been like this. Instead of creating better software they have always tried to add features with no consideration of backward compatibility.
No serious project should use PHP.
No serious project should use PHP.
This could not be further from the truth. Backwards compatibility is a big reason why PHP doesn't have <your favorite missing feature that is totally a dealbreaker and PHP is thus unusable>. Odds are if you look at their RFCs and internals mailing list you'll likely find proposals and even implementations for any BC-causing feature you can think of.
I hope they clean up some of that mess in PHP 9, but no, they're just going to add $shiny_new_feature and make the attack surface even larger. Like, why does the session handler even care about measuring upload progress?