One of the latest tricks is that if you have social media accounts yet no social media apps or accounts are loaded on your phone, or your phone appears to be a burner phone, they'll ask you why you didn't bring your main, primary phone.

So your "burner phone" needs to be your primary phone, which is something that is hard to go back in time to fix.

This sounds like a rumor to me. Plenty of people (including me) have no social media presence (unless you count HN as social media). How do you know that the person on whatevergram with the same name is me?

Because the ad networks associated with social media are really good at ascertaining identity.

People with no social media presence at all have been denied entry.

Citation?

I have a few social accounts, but no apps installed on my primary, 2.5+ year old S21. I prefer to visit via browser (firefox, mostly).

It's in general possible to only access social media via browser, not apps.

Which makes no difference since they’ll just ask you for your social media handles.

It makes a difference since if you're not logged in to them in browser they are less likely to know which ones you use.