Attention spans getting shorter isn't just because of television/social media. It's because of workplaces and expectation to always be paying attention to multiple threads.
I'll give an example of a low-level job where this happens. Pizza delivery.
You're hired for Pizza Delivery, but the business refuses to just pay you to only deliver pizzas, so technically you're also "on-call" to do every side job the the pizza place any time you're not out delivering orders. So you can just return from an order and be told to go to the back to prep X, Y, and Z, but you need to be listening for the bell in case you need to run up front and deliver a pizza. If you're walking past the front and a customer comes in and everyone else is busy? Drop what you're doing and take their order.
Every instance is always a "drop what you're doing and shift to a different task" and it goes on all day every day.
It literally teaches people to be distracted and unable to focus, because you're literally not allowed to fucking focus. Say you're finding your Zen place in doing dishes, you don't even get to finish the fucking dishes, because you're called back out to do more stuff in the front of the house. Later, you have to stay late to finish the dishes because it was too busy to ever get a chance to do them. Because fuck having someone who is just a dishwasher or just a pizza delivery person. We can't be paying people to sit around, tHaT's InEfFiCiEnT!
Actually, what's wholly inefficient is having people run around all day like chickens with their heads cut off to keep up when you could just accept that once in a while you're going to pay someone for doing nothing for a little while.
Studies always turn to blaming this inattention on social media, but literally our workplaces drive into our skulls that we're not allowed to focus on any one thing for an extended period of time and we should always be at the ready to shift gears into something entirely different, and come back later finish what we were working on. It's fucking absurd, and I think workplaces have a far more damaging psychological impact from it than fucking social media.
I'm going to disagree with you here on.
The issue with social media, for example tic toc, is that your attention span is reduced to seconds, not even minutes.
The sensory overload is here so large because you have thousands of possible options, with content often only seconds long, requiring no sustained attention. You also have no reason to stay focused on any particular object. If you are not immediately entertained, you can just switch to the next video and see if you like it better, and that's something you start carrying onwards: Don't like the article? Just skip to something else, there are (too) many options.
When we talk about thr work at a pizzaria, we don't talk about seconds (usually), but minutes or even longer - That's nothing unusual for you. Especially 'working and listening for the bell' is probably one of the more natural things for you.
In fact, I would go so far and say that work is probably a counterweight to shortening attention spans because you are forced to concentrate even on am unliked task for longer periods of time.