How the heck can such a simple thing still be debatable is a mystery to me. What's so difficult to make some measurements (if the one on the first page are not enough), blind tests or whatever is needed to come to a conclusion about if speakers break-in is a thing or not?
Or just check with woofer/tweeter manufacturers (the big ones) and the data they provide. Are they doing any break-in, at least with their top of the line products? If not, just forget it, they would had automated the process already if that was a thing. No manufacturer would sell speakers costing some thousand of dollars that would be terrible for the first 200 hours and then get better, if they suck from the beginning, they will be the same after 200 hours or two years. We just get used to how they sound because we want to hear the music they are playing and enjoy it.
Is Genelec, Neumann, Harman companies, or for that matter any company that is doing some research on the field recommending break-in? Especially for studio speakers, they would either break-in them beforehand or at least warn the users about this. Proffesionals don't have 200 hours to spend on break-in, time is money.
Until someone comes up with solid data that break-in is happening in a way that changes music reproduction substantially so we can perceive it, people would best keep in mind that if a speaker sounds terrible when they first listen to it, it's time to return it and go for something else.