I'm personally not a fan. Tried it a few times and found it far too distracting. Its about the putting stroke anyway; which is dictated by the putter face at impact, not a line on the ball.
I rarely have a problem with others doing it, but once in a while it does seem to slow down play. Not very often so I've never been too bothered by it. I did just come up with a good bet though - I'm going to challenge some of them to play without a line on the ball and see how they do. Put some benjamins on it.
Want a bigger challenge - play golf with me when I have a bluetooth speaker available 😃