Yeah, they used to leverage the barriers to entry into the generation market (before solar and wind, when only those with lots of $$$ could set up power generation facilities because the most efficient ones were big and very expensive ) to extract more money from customers, now they leverage the barriers to entry into the distribution market as well as the dominant market position left over from those before times.

Theoretically the barriers to entry into the electricity distribution markets are lower hence with time more competition will arise, but that's dependent on the laws passed by politicians to liberalize that market and politicians nowadays are very corrupt and design laws to benefit those who "reciprocate" their "friendly" consideration for their interests (and the most common way of doing so without being obvious is literally to thinker with those law to have artificial barriers to entry in the market thus protecting the market dominance of existing big market players)