The premise in that comment is that the budget comes down in tablets from Mount Sinai instead of a decision the Fenway Sports Group makes. And it is perfectly okay to question that premise. I mean I certainly do.
I mean, the Red Sox made what is probably a fair-ish baseball deal considering the variables. But they also punted on 4-6 prime years of someone on a HoF trajectory, and the current return is highly unlikely to produce a single All Star appearance, all while being one of the prime earners in an industry drowning in cash. That's just the reality. (note: the new version of the trade increases the probability of very positive outcomes of course, but it's still the usual math associated with young'ins)
The Sox are not unique here of course. The Dodgers are trying to reset too, and we know that the Yankees in recent years have spent a relative pittance of their revenue on the major league roster (and it's still a high payroll team). It will be a fun wrestling issue for the next CBA - the players right now get all of the downsides of a salary cap without the upsides the players in say the NBA get.