Someone explain the obsession with the claim that AI can't replace senior developers and can replace junior developers

I seriously can't go 5 minutes on the internet without seeing this claim. Bunch of people say AI coders will replace junior devs, but not senior devs. Gets 100+ upvotes no matter what the social media website.

Now the first question I would ask is, "do you remember what you did as a junior dev"? 100% of the time I ask this question I GET NO RESPONSE.

A junior dev is capable of developing an entire project from scratch with nothing other than stack overflow and some grit. This is in the pre-AI era. If you don't believe me, ask one of these "senior" devs who claims AI will replace junior devs and won't replace senior devs, what they remember doing as a junior dev, and what they were capable of.

Here is my claim: If AI can replace the average junior developer, it can replace the average senior developer within 6 months. If AI can't replace the average senior developer, it can't replace the average junior developer. Let time tell whether I am right and how well my claim has aged.