I always took it that they show the credits at all is because of the Unions.
That is, IMHO, sometime in the past, the Unions said that the credits must be shown. Those who show the shows, in order to get more advertising time, compiled with the agreement but did in a way for what we have now.
After all, face it, if they didn't need to show the credits, do you think they would?
Two things. First, speeding things up is nothing new. Supposedly, when Sci Fi Channel was showing UFO
UFO (TV Series 1970
in the 90s, they ran the show at a slightly higher speed to get more time for other things in the slot. Supposedly......
Secondly, when it came to Charmed and the broadcast doing advertising in the credits, especially for Steve Harvey (nothing personal, Steve), that sort of wrecked the good feeling for having just seen the episode. With that in mind, it would probably be better for them to skip the credits entirely.
Then, one more thing. Once upon a time in the 90s, I was watching
"Mission: Impossible" The Missile (TV Episode 1971) - IMDb
on FX (I think it was around the time an MI movie was coming out).
In the thrilling climax of the episode, like the last 10 minutes, ......
....... there were so many commercial breaks! It was like a minute of the suspense then cut to commercial. A few commercials later, come back to the suspense, then cut to commercial.
It was very frustrating but you know why they did it. As a viewer, I might turn off the TV after the show was done but they arranged it to hold my attention for those last commercials.
When it comes to broadcasting and commercials, one way or the other, they will find a way for their sponsors to get their time, find a way to have the highest probability of the viewer seeing them.