Back in the day when 10-speed was what we would now call 5-speed, you didn't have as many gear options, and tended to shift less often. Downtube or barend shifters worked OK for this. The more gears available today means more frequent shifting to find the perfect gear, so the easier shifting brifters or trigger shifters are prevalent. Shifting gears when climbing out of the saddle or simultaneously shifting the front and rear derailleurs are both much easier using brifters or trigger shifters.