That's just a habit. Instead of visually checking the flame, you just visually read the large 4 digit LED where you set this in steps of 10 degrees Celsius, or whatever. They (mine) already do measure what's in the pot. Or how would you explain that it goes within 2 to 3 seconds from 90°C and just a few pearls to boiling bubbles if you set it to 100°C when there are 2 litres of water in it?

They are more easy to work with, IMO. Just get a good one.