Jeff Ely has a hypothesis:
Everyone who has armchair-theorized why movie theaters don’t sell assigned seats in advance is now obligated to explain why this has changed and how that’s consistent with their model.
I will start. My theory was based on the value of advertising to movie-goers who must arrive early to get preferred seats and then are a captive audience. This has become significantly less valuable now that said movie-goers can bring their own screens and be captive to some other advertiser.