Hi

Being one of the "older Brigade" most of my performances were before electronic tuners came out.

I have used them and found them to be very useful as my hearing deteriorated.

I keep mine firmly fixed to my guitar and am not bothered about doing so. During a performance guitar strings can ( and do ) go out of tune.
I find the device aids my speed in re-tuning quickly and it helps me not to have to do the embarrassing and boring ( for the audience ) tuning and re-tuning.

Many of today's performers use them to a greater or smaller effect.

As other people here have pointed out we come to watch and listen to the music. For me, I don't really notice the tuners. Certainly they do not detrimentally impact on my enjoyment.

Cheers

MikeL2