LEGO requires patience, spatial reasoning and planning, imagination and dexterity. Bored with those blocks, well, you're going to have to wait until your
next birthday. Can't fit the blocks together? You're going to have to keep trying until you get the hang of it. Can't find that yellow block you need to finish your duck? You'll have to keep digging around in the big pile until you find it.
You can see why kids spend more time on tablets right? It's laziness.It's easier. Effortless. Also, lazy parenting. Especially when kids are small they need a bit of help from mum and/or dad with LEGO and building blocks. Don't need much help with a tablet...
I'm lucky, both my kids love LEGO, but I still have to monitor how much time they spend on the tablet.
My youngest son is nearly 2yrs old and loves the CITY LEGO trucks, and watching his dexterity improve just from playing with those and pulling them to bits is nothing short of amazing.
Also, what they fail to mention here is that building blocks are not for all kids. Some kids just don't get it. Just not interested. And that's got nothing to do with modern technology because I saw that lack of interest in some kids more than 20 years ago.
Last but not least, there's been a big fuss in the media here (NZ) about kids going to school and lacking the dexterity to hold a pencil, being unable to recognize their own written name, etc. From memory technology got the blame as well. Not enough time spend interacting with mom and dad.