That is one big reason. Another reason often cited in 1980s and 1990s was synergy, although the term has dropped out of fashion. Synergy is the notion that the various elements of the combined companies would reinforce each other, in effect that the whole would be greater than the sum of its parts. The reality can be quite different. Various studies have shown that the majority of mergers do not add value for shareholders.
Merger mania tends to occur in waves.
In the 1960s, conglomerates were all the rage, as companies gobbled up businesses that bore little relation to each other. ITT was the classic conglomerate of that era, a hodgepodge of different concerns - from manufacturing to insurance. By 1995, the company split itself up. We are now experiencing another wage of mergers across the board, cars, pharmaceuticals, telecommunications, finance, the list goes on. But from the academic studies, most mergers, like marriage, are a triumph of hope over experience.