Is spam really the best build?

In the interest of better list building, let's try to answer the question: Is spam really the most competitive way to build an army? I dug up the following list on the popular forum Dakkadakka.

• HQ: Librarian with Jump Pack, Shield and Unleash Rage
• HQ: Honor Guard with 3 Meltaguns, 1 Flamer, Jump Packs
• EL: 2 Sanguinary Priests with Jump Packs 150
• TR: 10 Assault Marines, 2 Meltaguns, Power Fist
• TR: 10 Assault Marines, 2 Meltaguns, Power Fist
• TR: 10 Assault Marines, 2 Meltaguns, Power Fist
• TR: 10 Assault Marines, 2 Flamers, Lightning Claw
• TR: 10 Assault Marines, 2 Flamers, Lightning Claw
• HS: 5 Devastators, 4 Missile Launchers
• HS: 5 Devastators, 4 Missile Launchers
• HS: 5 Devastators, 4 Missile Launchers

Total: 2000

Is this list built through the matrix of Unit Purpose, Army Cohesiveness, and  Unit/Army Efficiency. Or, is this list built on the principle of 'If something is good, take 4 of them'??

I am of the opinion that this list could easily be played well on the table. However, the internet argues that this type of list is competitive and lists which have different units instead of carbon copy units (spam) is not competitive. I do not agree with that statement.

 I believe that a list built with purpose, units that work well together, and efficiency can include varied units and need not have the spam factor to be competitive. The table-top general must be able to focus on the purpose for his units/army, analyze the developing events on the battlefield, and implement his strategy towards accomplishing the mission. The cunning general can accomplish this with different and varied builds.

What do you think? Is spam the only way to go? Are these "Internet Experts" actually experts? Can the true table-top general generate continued success with lists which the internet experts do not consider optimal?