To make the life of hostile foreign powers harder? Currently they are allowed to run code written by them on the devices of unsuspecting citizens, and curate the content these citizens watch.
The argument sounds like a non sequitur: because we cannot defend against all threats, we should not defend against any threat.
We each have our priorities. I want to secure government secrets held by OPM/US Treasury and key infrastructure like telecom networks, and others want to secure the average citizen's social media feed.
We can have different priorities for what is more impactful, easier to secure, and less restricting to fundamental freedoms without resorting to black and white thinking.
Cybersecurity is failing across the board causing damage worth 1000x of what it would cost to secure these systems.
I am all for securing critical IT infrastructure, I think we agree on that.
Hostile powers will exploit any vulnerability they can find. In democracies, ordinary citizens are a target. In Romania an election was annulled, and TikTok specifically named in the investigation: https://apnews.com/article/romania-election-president-george...
Therefore I think we should not underestimate this threat. I admit that doing this in a way that preserves fundamental freedoms is not easy, and I don't claim to have the answer. Consider freedom of movement: few people seriously deny the need for passport checks on international borders.
The argument sounds like a non sequitur: because we cannot defend against all threats, we should not defend against any threat.