Leon - the company which developed Crysis has 186 employees, so they can afford to test on just about every platform out there. (Plus, their product was distributed by Electronic Arts, which probably also has a few computers laying around.)
I'll do my best to make MA3 run on as wide a range of equipment as possible, but the combinations out there are really overwhelming. The Beta test team has a couple-dozen computers, which seem to represent a fairly good cross-section of equipment.