Some is overzealous H&S, some of it is having 30 blokes working in a small area fighting over sockets and trailing leads all over the place....
Have you tried using your mains powered tools up a ladder with your head in a void? If you trip you might strangle yourself with the power leads.
If you are working outside there may not be any power, you can't drag a genny big enough to run a big sds with you as well as ladders and all the other kit.
They all have their place, I have a mains sds drill and a battery one. If you have a workshop then mains power makes sense.