The same who say that never gets around to the tweaks
Until you run into a hard wall trying to integrate new features that customers request which break the entire system and before you know it, you're still running on C# 3 while all of the other APIs and companies have long upgraded to C# 8 (or switched languages altogether). Then your wildfire turns into a firestorm and your customers start calling in.
And they're pissed.
The EU has a study which I cited in a previous posting indicating that price competition requires four substantial sellers. One is a monopoly, two tend to implicitly cooperate as a duopoly, sometimes there's competition with three but often two of those dominate as a duopoly, but with four, price competition usually appears. It takes at least four players to have a free market.
So, less than four players in a market, and Government constraints kick in. Breakups, blocks on mergers, restrictions on expansion, higher taxes and closer scrutiny for the top 3. The US used to do stuff like that. The EU now does.
Now that's a free market.