Why would engineers spend more money to design herringbone gears?

Why would engineers spend more money to design herringbone gears? A gear only needs to mesh to work, right? That is one of the biggest misunderstandings about gears. Around the early 1900s, engineers found that herringbone gears could run much more smoothly. Because ordinary gears could transmit power, but once the speed got higher and the torque got larger, the teeth started acting like they were constantly hitting each other. Every time they meshed, a whole row of tooth surfaces contacted almost at once. The bigger the machine, the stronger the impact, vibration, and noise became. Then engineers had an idea. Why not make the teeth angled? That way, when the gears mesh, the whole tooth does not hit at once. Contact starts from one end and slowly moves to the other. The force is not slammed in instantly. It is transferred little by little. So helical gears are quieter and smoother. But a new problem appeared. When a helical gear transmits power, it does not only make the other gear rotate, it also creates a sideways force that pushes the shaft in one direction. The bigger the machine, the stronger that force becomes and the more pressure the bearings have to take. That is when the herringbone gear appeared. Engineers placed two opposite helical gears on the same gear. The left side pushes the shaft one way, the right side pushes it back the other way. The two forces cancel each other out, so it keeps the smooth meshing of a helical gear while solving the sideways shaft force. But because it is harder and more expensive to make, not every machine uses herringbone gears.