What was the oil price when Sir Frank worked his magic?
Jet engines DIRECTLY produce Thrust, and Fuel Flow is directly related to Thrust output.
It may be
related but it's by no means dependent
only on thrust. It varies significantly with speed.
The dotted line in your diagram is a good representation of the thrust available for a jet. Thus if you're looking at angles of climb to find maximum excess thrust, or if you're solving a ceiling problem where you want to know what speed permits you to stay level at the ceiling, then I think your diagram explains it well.
But the dotted line is not a good representation of the thrust
per unit fuel consumed. For example the graphs that I'm looking at (from Anderson's Aircraft Peformance) for an RB211 show a Thrust Specific Fuel Consumption proportional to approx (1 + 2*M) at sea level, and proportional to (1 + 1.5*M) at 10,000 ft.
Let's take the second for holding. With the speed of sound at 660 kt (warm day at FL100), we can get an idea of the gradient:
000 kt TSFC = 1.00 unit
110 kt TSFC = 1.25 units
220 kt TSFC = 1.50 units
330 kt TSFC = 1.75 units
So for thrust available per unit fuel, it looks like:
000 kt -> 1.00 unit
110 kt -> 0.8 units
220 kt -> 0.67 units
330 kt -> 0.57 units
That's much steeper than your thrust-available line, and shifts the speed for max endurance down considerably further, though not down as far as the Vmp point.
On a rather more abstract level:
Aircraft need Thrust, they always have, and probably always will.
Aircraft don’t need Power, they never have, and probably never will.
As with many problems in physics, you can solve this equally well using force (thrust) or multiplying by speed and using power instead. The maths has to work in both regimes. Which one you choose depends on which is more convenient, and it's entirely appropriate to choose force when your thrust doesn't vary much with speed. So in that sense aircraft need both thrust and power.
What is less arbitrary is the nature of propulsion based on combustion. A ton of fuel contains a certain amount of chemical energy, which the engine converts at a certain rate to power used for propelling the aircraft by pushing air backwards.
Naively, one might expect the efficiency of this process to be independent of speed. For props, this is a reasonable assumption. For jets, the efficiency increases with speed, and leads to a power specific fuel consumption with a very strong negative speed dependence. This makes it almost worth dividing through by speed to consider the thrust specific fuel consumption, which will have a strong positive speed dependence. That simply reflects huge inefficiency at low speeds, not some magical feature of Whittle's invention that defies energy conservation.
Props are also less efficient at turning fuel into useful power at low speed. The difference between props and jets is only one of degree, in the slope of the speed dependence.