Because it happened in the past as well. And the big tech companies were split, cut down, and destroyed. Big tech was not IT in the past but other “advanced technologies” at their time.
The past is a good reference to learn from, but it can’t be a blueprint for the present. There are different circumstances between then and now which complicate things, like the aforementioned big money in politics.
Just a few in the US - and they were all different at that time. They were all intertwined with politics at their time. Quick google search though, not sure how good the sources are:
Railroad: https://digfir-published.macmillanusa.com/roark7e/roark7e_ch18_4.html
Steel, oil, and tobacco: https://19thcentury.us/19th-century-monopolies/
Or just recently: take a look at China. How Chinese Big Tech influence on society was crushed and control was taken back by the Communist Party in the past 5 years.