I guess my take on that is that there are multiple "recent" TV shows that are as good as TV has ever been, but that the percentage of great TV is diluted by the sheer volume of shows being made on the old traditional broadcast and cable networks, plus the glut of streaming platforms making original content, most of which is garbage.
So, similar to music, it's not that great TV isn't out there, but you probably do have to dig harder for it than in days gone by. Of course, "great TV" is likely to be subjective.
Movies.....I dunno.....it is way harder for movies to capture my attention the way they used to, and I like a lot of less of them than I used to, and my movie searching scope is exactly as wide as my TV scope, meaning everything from mainstream theater releases to original content produced on several streaming platforms we subscribe to. It seems that in general, I have personally shifted in preference, gravitating toward stories that are given a long time to develop with many, many hours of character development. Thus, TV series become preferable to 2 hr movies.
BUT, there still definitely are movies being made I enjoy. Sometimes they're super good, and that to me is a great achievement, for any era.....making me care so much about the plight of characters I only just met and whose stories take place entirely within a couple of hours.
That's cool, but it's really a "you" thing so I don't think it would be fair for you to say something like, "Movies just aren't as good as they used to be" or "there are no good movies being made anymore." Just because your preferences have changed, doesn't mean the industry has.
And I'm not really trying to single you out, I just see a lot of this sentiment from many posters here on the board, and from my viewpoint, it has more to do with them and their preferences or biases, than it does with the original art content being produced.
As for TV being diluted, I'm not sure I can agree with that. The sheer amount of content is much much higher now than it was 3-4 decades ago, but I don't think the ratio of good-to-bad has changed all that much.
I have a pretty low opinion of where mainstream TV sat 3-4 decades ago, with so many bad shows from the 70s/80s/90s. And my impression of it hasn't improved at all with all of the truly horribad shitty "reality" shows and "competition" shows that have proliferated since then.
So I don't think the ratio of good/bad has really changed all that much, and since the sheer volume has increased manyfold, it means the total amount of "good TV" being made, is actually much larger than it was in decades past.
Do you have to search harder for it since there are more than just 3 networks plus PBS like we had in the 70s? Sure. Does that mean it's not out there? Of course not.