As ever I've been among the slowest to fully embrace crisis actors. It was such a big idea during Sandy Hook that I couldn't digest it all in one go even though I could see that it made sense but didn't make sense in terms of being a fully synthetic event.
The pictures of the guy with his leg blown off at the Boston bombing have now been debunked and he may well be a crisis actor amputee veteran of Afghanistan. There is no meat on the stump in the above video and they put some on later for added effect. There can be no denying this.
The only "generous" hypothesis I can think of is that an event is pre-identified, then neutralised and use for information warfare purposes to give the impression that it went ahead successfully to the masterminds. If anyone else has a better idea I'm open minded.