Mirrorless cameras have become very popular because they are light and not too heavy on the pocket.
Easy to bring along with you, good quality JPEG's out of the camera.
To some having both a mirrorless camera and a Dslr (FF) gives them the option to shoot without thinking about the weight factor and using their Mirrorless camera on trips or holidays, without looking too intimidating..lol
Fujifilm has quite a bit of followers and popularity is rising with their cameras.

The best way to pinpoint is
Budget
What are you going to use it for
A camera is only as good as its owner..

I am sometimes using the pocket cameras more, am quite happy with them although i have Canon and Nikon Full Frames, due to portability and ease of use.
Whenever i cycle , i tend to carry the pocket camera and stop to use it if i see anything interesting.

But i guess the ones who use their cameras on a Pro basis have lots to say...