People keep saying this and I want to call bullshit. First of all, Netflix and streaming weren't that big when Saturday blocks still existed, and not many kids knew about torrenting sites so it's basically a non-factor and akin to saying "video games killed Saturday morning shows". Vortexx died around 2012 I think, that was when Netflix decided to try of the idea of original shows
And secondly, as a kid I used to watch Saturday morning shows alongside Nick and CN. Why? Because contrary to the "kids don't have to wait till Saturday mornings bs" there were some shows those networks simply didn't carry or didn't have the newest episodes of at the time, Pokemon didn't start airing on CN until give or take 2003 and at that point it was Advanced Generation, and CN was playing catch up with the original series, same goes for shows like Power Rangers, Yugioh, Digimon and the like. I chose to watch Kids WB instead of Toonami Morning Sun despite how much I desperately wanted to watch both but couldn't.
And finally there's the "educational programming" bit. Let me ask you, did the thought of Bill Nye the Science Guy make you groan? How about Magic School Bus? No? Because they were still well put together shows that had a lot of effort behind them. Kids aren't that picky, educational or not they still caught plenty of attention.