because the "stuff" in question is social networks who live, as the name suggests, off network effects. To have a European LinkedIn would require everyone in Europe to switch at the same time. Which can be trivially arranged, we just would need the courage to ban LinkedIn and every other American social media company. We'd have a clone up and running in a month. You only need to look to China who did exactly this.
That's socialist dictatorship. Why do you want the EU to be more like China, instead of the EU being more like the US? It will result in further isolation and decline of Europe which sorely depends both on the US (and China) for survival.
I don't want to, but if people like you represent how Americans think, with nothing but contempt for Europe and only obsessed with power, then the Chinese were right about who Americans are and we were naive.
Then achieving autonomy quickly is necessary. And it's not about isolationism, just different priorities. The Chinese aren't isolated either. It's the US that's isolating itself right now as other countries see how they're treated.
I think it's much more the other way round. As a not-American, the amount of contempt I see Europeans having for Americans for not "valuing family" (i.e. lots of free childcare and maternity pay), or generally not having really expensive social programmes, and having medicine prices based on the R&D costs, when the only reason they can do that is because the US taxpayer funds most global shipping, and most health R&D in the world, is much higher than the reverse.
Saying "oh we should be autonomous" won't ever remove all the free help the US has given those countries in the past, even if they stop relying on it in the future.