Why do scientists use statistics?

Answer 1

There's a lot of types of scientists and so the answer differs somewhat for the area of science. In the physical sciences, there is a need for precision in the measurement of unchanging quantities and that requires multiple measurements and even trimming off the more extreme observations to get the average of the remaining observations. See the meta-analysis done by Stephen Stigler of how some removal of extreme values can improve the measurement of a quantity. https://projecteuclid.org/download/pdf_1/euclid.aos/1176343997

Ecologists are often dealing with changing values and so there is a need to both get multiple measurements of the existing value and to follow it up with multiple measurements of its changed value. It can then be very important whether a population is declining or rising or staying the same and it becomes even more important to get high quality, multiple measurements to discern what are the most likely reasons things are changing, such as with studies of climate changes.

Hope that helps!