I can name lots of examples. Before 1982 there were like 20+ companies who wanted to produce video game console.
Did we need 10 different commercial unixs.
Also, the consolidation results in companies that have the capital to invest. Having LM, MC, Boeing and Airbus all making widebodies didnt make sense and resulted in issues for both tri-jet producers. Airbus was the winner in that situation because neither company could invest in twin-jet widebody.
The idea that the economy would be awesome if there were only small companies doesnt really hold up.
So just saying consolidation bad 100% doesnt really hold up.
The telecom are special because they were all state owned then privatized, they are mostly not the result of consolidation.