Inflation is just an enormous fudge factor to explain why the universe is far more uniform, than can be explained within the confines of the time frame of BBT.

Dark energy is to explain the parabolic curve in the rate of redshift, that could not otherwise be explained by the energy of the initial event. It was originally assumed the rate of redshift decreased at a steady rate, from apparently close to the speed of light at the edge of the visible universe, to the much more gradual effect of closer galaxies. What was found, was the rate dropped off rapidly, but then settled into a more stable rate. According to the premise of BBT, it was like the universe had been shot out of a cannon, then a motor kicked in, to sustain a stable rate. Dark energy is the motor.

Yet what we see, from our point of view outward, is redshift starts off slowly and builds, eventually going parabolic. Which would be far more efficiently explained by redshift being an optical effect compounding on itself.

Yet that would mean the last hundred years was a wild goose chase, so it's better to just ignore the principle of falsification and stick on a few patches.