I've used angle grinders a lot but always ones about 3 times the size of the one in Samon's photo. So a lot more power, a lot faster, a lot rougher and a lot more aggressive. Yes they can be used with finess (I've used them to remove paint from steel where I've only wanted to take the paint off, not the steel).
Maybe because I'm used to big models that are very fast in their steel removal that I'm so dismissive of their use for renovation of edges. It's not just the heating issue, it's that a slight slip will cut a huge gouge in the edge making a small reprofile job into a major blade reshaping.