As a kid I would sometimes catch the Simpsons on TV. I didn’t love it, but it was perfectly serviceable. Then I kept hearing online when I got older that people thought it was bad now and was better in the earlier scenes. One day I watched the very first episode in order to test that. The one where they find the dog on Christmas or something. The quality was exactly the same. Only the animation had changed. If it were written today, I wouldn’t have noticed the difference.
Conclusion: The Simpsons hasn’t gotten any worse since it started.
Granted, in retrospect, the sample size is to small to provide an accurate judgement, but like I said, I don’t care for sitcoms, so I can’t be bothered sitting through more of it. It was mildly amusing then and is mildly amusing now.