Just to add another note to my above comment. At Dow in my day we used to use a PYRO computer model on our ethylene cracking furnaces. By programing in the geometry of our furnaces we could adjust cracking variables to change the output products to maximize returns based on fuel value or chemical value. So, if naphtha from a refinery was priced downward to match crude oil downward trend, we could adjust cracking variables on our naphtha crackers to maximize profits based on fuel or chemical value.
Our competitors also used the same models so they would adjust their products downward to match competition. Hence, their products followed the price of crude.
I used to track hydrocarbon pricing during my days at Dow (60-93). Dow doesn't own a refinery, but it does buys products from them. e.g. naphtha, propane, butane, pentane, hydrogen, methane. These products are priced on two bases. One is an energy base (BTU value). The other is as a feedstock for commodities (chemical value). If it's a cold winter, the refineries price their products on an energy based system (BTU value). If it's a warm winter and commodity prices are up, they swing to pricing based on commodities' e.g polyethylene, chemical valued commodities. So, in this respect, it's hard to figure why Dow is tracking crude prices. We've had a hard winter and prices may be currently following BTUs. The U.S. market is also up, so there should be a swing to chemical values.
This may partly explain your question. It's a good one. So don't give up till you totally understand it. My pricing models I used at Dow agree with your argument.
For 33 years at Dow, I helped design co-generation plants (3) to generate steam and power from natural gas. This venture in Texas will allow Dow to buy 200MW of power from a wind farm. I wondered what this could displace in a co-generation plant in terms of high pressure steam used in power generating steam turbines or displacing natural gas in a Hot Gas Turbine used to generate power. So, I hauled out my old Dow co-generation data and translated some numbers for us old technocrats.
In a hot gas turbine, 200MW of power would require 262,971 lb/hr of natural gas.
In a total condensing, 2 stage, steam turbine, 200MW of power would require 1,728,000 lb/hr of 1,484 psia steam at 974 deg F.
As an old technocrat myself, this is quite an impressive measure in reducing other non renewable fuels. Good work Dow.