So by definition you just made my point by stating the highlighted above Mark ISN'T(that by definition means he WON'T not that he can't) He can set the payroll at whatever he wants. So yes, it's much more appropriate to say they WON'T spend the $$, not they CAN'T spend the $$.
No one says they have to go out and spend like the Mets.
They spend money on FA's once in awhile but when they do, they are mostly one year deals, or smaller two year deals(like Wong for instance). there is absolutely NOTHING stopping them from going out and signing a big $$ FA to a multi year deal, If they would choose to do it. Heck, there's nothing stopping them from resigning Woody, and Burnes or Adames if they would CHOOSE to do so(and adding a big $$ FA). they are just choosing NOT to.
If you build it, they will come. Sure, their revenue stream isn't as large as other teams are, but I'd bet dimes to dollars if they put some big name players on the field, fans would show up more than they do now. That helps drive revenue. Heck, every team just got an extra 30 million this year, That essentially buys you a "free" year of a big $$(multiple year) FA. They choose not to do it.