There are some competitions with crowds. They're effectively strongman comps but solely with stones, and they're getting more popular.

Generally, you're alone or in a small group. So your idea of a lone man stalking across a Scottish moor isn't too far off. Usually no lycra though.

A bit like this in Scotland: https://www.thedinniestones.com/

For the Icelandic hussafell stone you can just drive up and have a go I believe.

Perhaps a giant in a holocaust cloak lurking in an outcropping waiting to hit you in the head with a small boulder.

Which doesn't seem very fair.

Inconceivable!

Edit: the parent post references the movie The Princess Bride and my reply follows:

https://knowyourmeme.com/memes/you-keep-using-that-word-i-do...