Why did pentode tubes replace tetrodes in many electronic applications?

Pentode tubes largely replaced tetrodes because they resolve a specific performance issue caused by secondary emission.

In a tetrode, electrons striking the anode can knock other electrons loose from the plate's surface. Because the tetrode's screen grid is maintained at a positive voltage, it can attract these secondary electrons, which interferes with the tube's operation and limits its performance.12

The pentode solves this by adding a third grid, known as the suppressor grid, placed between the screen grid and the anode. This grid is maintained at cathode potential, creating an electrostatic barrier that repels secondary electrons back to the anode. By preventing this interference, the pentode provides greater amplification and more stable operation than the tetrode, leading to its widespread adoption for most vacuum-tube functions.132