The sound engineer continues and tries to maintain that goal every night, show by show. It's not that the actors have gotten worse and aren't able to project. In the past the reality was, when you went to shows your concentration level had to be so high to actually hear. Therefore, there is some attempt to bring that into the theater. If the equipment supplied is cheap - you get what you pay for.
Sound checks are important.
It could be brilliant equipment, but if it's been set up incorrectly, then you have a problem. During the recent Tony Award telecast the audience could occasionally hear Tony winner Martin Short perform. Martin Short's microphone was cutting in and out. When he came out his hat was right on top of the microphone, pushing the microphone head. He probably squeezed his hat on so it wouldn't fall off.