Why are trigger shifters so widely used, instead of the twisting grip shifters(revoshift)? I recently rebuilt my whole bike. It was in terrible condition. I also decided to get a new freewheel with more speeds. While i was doing some research and looking through shifters and freewheels, i found out that the twisting grip shifters were limited to only 6 and 7 speeds. I couldn't find any twisting shifter with more than 7 speeds. I personally find them so comfortable, convenient, easy and way faster to shift than the common trigger shifters. I finally decided to get rid of the old 6 speed freewheel and install a brand new 7 speed freewheel with a huge low gear for crawling.
Why are trigger shifters so widely used? I don't see any advantage.
Update: Many people said that twisting grip get stiff over time and are difficult to twist. Yes they get a bit stiff over time, but from my experience they still aren't hard to twist at all
Below image of twisting grip shifter
In the context of a high-end MTB designed to go quickly over difficult terrain, trigger shifters have the following advantages:

They can be operated using only the thumb, without changing the grip, so the index finger is always ready to brake.
Getting mud on the gloves does not impair operation.

Modern grip shifters do exist, Sram makes a wide range of those, and in my experience, the cheapest option (the GX model) is very reliable and performs very well. For completeness sake, grip shifters have the following advantages:

Ability to shift through the entire cassette in one motion (assuming a single chainring setup, typical for the context), useful before a sudden steep hill.
Absence of a protruding element to be hit by the knee in case the leg unclips unexpectedly.