The reason for that is entirely Youtube's fault.
Back a few years and the primary objective of any videomaker was to make their videos as short as possible. The kiss of death for any uploader was having a 4+ minute runtime and for people to see that and simply not even click. It was all about sharing quick, funny, to the point stuff. However, if something was over 4 minutes long, or even, shock, horror, over 10 minutes, it meant it was because it had to be and all that 10 minutes would be content.
Then, suddenly, fast forward a bit and Youtube changed the algorithm for getting noticed. Out went clicks, likes and comments (though not entirely) and in came retention. YouTube was now interested primarily in users who can hog their viewers for as long as possible, preventing them from going elsewhere and, more importantly, making them sitting ducks for lots of adverts within the same video.
All of a sudden out went the quick memes, 30 second fails, today's cat video and in came popular people who just talk to the camera about stuff, often with a clickbait title but very little content related to the clickbait.
The biggest winner of this turn of events was, ironically, exactly the channels which give YouTube a bad name, namely the political or un-pc drama channels who's content is basically regurgitating the day's news headline but stretched as thinly as possible over 10 to 20 minutes.
You can even see it's effect on random channels like Cinemasins or PewDiePie, where once they would churn out bi-weekly 3 minute videos but now the exact same content gets stretched to 20+ minutes. Of PewDiePie's 29 videos this month, the shortest is 11 minutes 14 seconds; go back just to Aug 2016 and of 20 videos the shortest was just 2 minutes and 1 second and only 2 were over 20 minutes long, the vast majority being around the 6 minutes mark.
With Cinemasins, they reupload a lot of their old stuff due to changes in copywrite practices and it's so noticeable. This week they reuploaded their take on the easily mockable movie Battleship, the video was from 2012, it was just six and a half minutes long. But for a new movie with barely anything mockable, such as Paddington 2, they stretch the video out to over 20 minutes, most of which is just spewing random stuff to cash in on a popular title.
And this is an across the board issue. So all your specialist how-to video makers are having to employ the same techniques to stay noticed. Same with recipe channels, fail channels and all etc. So when Dart says "it's more like TV now" [paraphrase], it's actually precisely because that's exactly what google wants it to be and is a wholely accurate perception.