Because having "big tech" is a sign that the government has completely failed to enforce anti-trust laws and allowed dangerous concentration of power to occur. It's a symptom of a disease not some desirable goal.
The EU doesn't need or want "big tech", it just needs "tech". It needs generous public funding for infrastructure, open source, and it should aim to build upon open standards whenever possible.
We don't need domestic monopolies that are just going to fuck us in the same way that US corporations fuck Americans while we all pretend to enjoy it for the sake of looking superior to the other camp.