Nothing is stopping companies from acting in a way that isn't anti-customer, other than the fact that anti-customer behaviour is more profitable than acting properly in the single market. We're finally seeing these externalities be addressed and be made slightly better, even if there's still so much more that could be done.
Probably nobody wants it to happen but if it were to happen, well, I prefer regulated companies than monopolies.
I don’t think that will save you from monopolies, though. Network effects are strong.
You vastly underestimate how interconnected and dependent the modern tech stack is. EU computer engineers would be thrown back to 1950s if they could not depend on decades of US engineering and services.
I say that as a European.
EU is clearly playing a losing game here and is well on track of becoming the world's largest outdoor museum.