Question About the Diversity of Builds

I'm incredibly curious what the general public thinks, in regards to how many ways there are to build a champion. Sometimes I see the "wtf is your build" text directed at people, including myself sometimes, and I'm always befuddled by it.

I'm not building a Rod of Ages on Garen, or a Sunfire Cape on Ashe, those are obviously not helpful. I tend to be in normals when the "wtf is your build" text happens. Usually in Ranked people tend to build standard items.

How many ways can you viably build a Garen? Or Shen? Or Xin?

I will admit my question stems from a recent experience of my own. I played Shen, and the following were my team's scores. Me : 6/3/16 Graves : 4/7/9 Pantheon: 4/13/9 Malphite : 9/5/9 Jax : 8/10/1

Panth and Graves had a string of bad luck, getting caught out in enemy jungle territory. It happened a couple of times. And I'm sure in frustration they tabbed open the scores and were furiously searching for someone to blame. I think its also worth noting that Pantheon was a SUPPORT...

I wasn't carrying, but I was obviously not doing bad at all. And 28 minutes in with 16 assists, clearly I was helping everyone and making global plays. I got the "wtf is your build" from Pantheon and Graves. "It isn't working", they said.

This was in normals. I was testing two items, yes, but they both featured Health, AP, and AS. All things good on an agile ninja Shen. I wasn't going tank Shen.

So my question is, how many builds are there that a champion can have? If you believe there is only one viable build, then I assume you strongly believe Shen can only be built tank. Or you don't understand that Champion as well as I do.

If there is only one way, more or less, to build a champion, then by definition doesn't that mean that our champion and item selection is wide, but shallow?

I'm level 7 mastery with Shen. My lifetime totals are 115/76/261, and averages are 6.1/4.0/13.7, and I usually build tank/bruiser.