Check out this screenshot from a video taken by Jean Rathle. Then scroll down to the video. Watch from about 2 minutes in and witness Steve B. taking out Al M. Steve was definitely barging here (pretty common thing in formula fleets). You'll notice that in his race report, Steve doesn't really dwell on things here - he clearly recognized he fouled Al (which is why he did his circles), and because it took him a while to sort things out after the yardsale, he had a crappy race.
Not to pick on Steve here; he's a seasoned racer, and he tried to walk that fine line between not running into people and not being over early. I'm sure he would have pushed up (and taken the OCS) rather than crash - if he could have. But it looks like he either didn't see Al, or things were happening too fast for him to process and react. Same with Al - it's pretty clear that even though he's looking up, Steve was in his blind spot and caught him completely by surprise, so he never had a chance to take evasive action, and while he apparently had a remarkable recovery to take second in that race (way to go, Al), I'm sure he realizes how lucky he was that nothing more serious happened.
I said above that barging is pretty common in formula fleets. It's also a pretty risky strategy - if you're coming down the line at speed, fully lit with the fin loaded up, you have limited ability to take evasive action. So if someone pushes you up, you often can't go below and around them, and you end up going over early instead. If things go wrong in your evasive action, you're now forcing the other guy (who has the right of way) to take evasive action and mess up his start. Or you crash, which is really slow under the best of circumstances, or could get someone hurt if you're not so lucky.
For slower fleets (keel boats, slower dinghies), barging almost never works - you can pretty much rely on someone to come up below you and push you hard, and in competitive fleets, bargers will get pushed into premature starts almost every time. In formula, that's a bit different - there's a serious risk in pushing a barger up, and as Rob Hartman used to point out, swimming is indeed the slowest point of sail, and who wants to get hurt or get their gear smashed up and sit out the rest of the regatta?
That has led to barging being ubiquitous in formula racing - especially in local races (big, aggressive fleets at major events tend to close the door at the boat, so bargers usually don't even get a chance to run down the line - they end up peeling off to avoid getting pushed into the committee boat). And sometimes, that can lead to a situation where if you set up for a proper start, you end up getting screwed in the process - so even seasoned racers might choose to be part of the happy parade of bargers zooming down the line at speed.
Just remember that when you're barging, you're taking a pretty significant amount of risk. S&*t will happen sooner or later when you barge, and if it does, you had better be prepared to bail. Don't count on the people below you to just acquiesce and be cowed - sometimes, they'll push back. I don't have a problem with racers taking risk, as long as it's reasonable given their skill and the conditions (Steve B., for example, can usually be counted on to be in control, so I wouldn't hesitate to push up on him a little - if that makes him OCS, tough luck, and I'm sure he wouldn't complain about it).
Just as long as we all remember that at the speeds we're going, and given all the pointy/sharp/hard bits on our gear, cutting it too close can have some pretty nasty consequences. It's not a contact sport, after all.