Well, according to the blurb on MLBTR, they are willing to include prospects and possibly eat up to half of what Myers is owed. "Giving up prospects" doesn't mean "scraping the bottom of the minor league system for warm bodies to include' The goal is to give up something enticing. Teams do include good prospects/players sometimes just to unload a contract. The Pirates included Reese McGuire, who was a twice-ranked prospect by Baseball America, just so they could unload the final 1.5 years of the contract of Francisco Liriano.
As a Yankee fan, you might like to play the "give up money rather than prospects" game. But not every team has the luxury of giving up as much money as the Yankees. And as many prospects don't turn out as good as hoped anyway, sometimes using them as currency becomes as good as getting something for free. And the insanely deep farm system that Preller has built is now being used against him by ownership, who has insisted that the parent club perform better and that the farm be used to make sure this happens.
I do think the Sox will have to eat the Myers contract, and also are unlikely to get Margot, who is still useful to the Padres. However, if the Padres were willing to keep their cash and include the redundant Josh Naylor, count me in.