WBL is based on average number of encounters per level × average treasure per encounter at CR. The broken part of the system is how much wealth is being given out, not the assumptions behind WBL. Also, using gold as the base monetary unit is screwy.

The very first time I played D&D in 1976 I rolled up my first character (average Int and Wis = Fighter). The GM rolled some dice and said, "You have 90 gold pieces." At this point I only knew that 1 gp = 20 sp. I thought, "I'll be able to buy armor, a horse, maybe even hire a couple men at arms." Ha ha ha!

I knew that around 1900 "a dollar a day" was actually good money, many laborers didn't earn that much. Years of visiting battlefields and forts told me that Revolutionary War soldiers earned 20c/day, and Civil War soldiers about double that. Years of Sunday school taught me that 1 denarius/day was an average in Jesus' time, and the denarius was about half the weight of a dime.

So, I had this notion that one or two silver pieces a day was the typical earning power, so my 90gp was 3-6 years' income for a peasant. Then I saw the price list and I could only buy rations & gear, a sword, a wooden shield, and something called "ring mail" that nobody could tell me what it was.

When Gygax & company made gold the common medium of exchange, and then made it almost worthless, it broke the mental link with our natural expectation of the value of gold and silver. Even for people who don't know solid figures about historic wages.