Nonsense. There is no sports shooter on earth who shoots f/2.8. Not a single one.
I find that shooting wide open is common among sports photographers.
Stadiums have artificial light, so the need for wide apertures is not the same as low-light situations.
Nevertheless photographers use lenses such as 400/2.8 wide open, to provide a clear image of the athlete and blur out those advertisements I mentioned.
In typical ice skating arena, the lighting allows 1/1250s, f/2, ISO 2500. That's not quite fast enough to avoid movement blur in jumps and pirouettes, one should probably use 1/2000s or faster, but I make this compromise to get better tonality. With an f/4 lens you're stuck with ISO 6400 and shutter speeds that are not quite sufficient to freeze the fastest movement.
To simulate what happens with an 400mm f/4 lens, here is an approximately 2x crop of Evgenia Medvedeva (in her world record performance) taken with a 200mm f/2 lens wide open. 200/2 wide open cropped by 2x gives similar angle of view and depth of field as a 400/4 would.
https://www.flickr.com/photos/ilkka_nissila/33613997871/in/dateposted-public/As you can see the ISU text is clearly visible and readable, which is acceptable in this image because it gives context but most of the texts in those boards are from advertisers and quite distracting. If I had used a 400mm f/2.8 lens, such texts would probably have been blurry enough to not be a distraction and I'd have better signal-to-noise ratio and sharpness as well.
Ideally I would like something like this
https://www.flickr.com/photos/ilkka_nissila/38263777715/in/dateposted-public/where the skater was close enough so that only a slight crop was needed at 200mm, f/2, but I'm not usually so lucky.
An example of how advertisements can get through (70-200/2.8 wide open but cropped):
https://www.flickr.com/photos/ilkka_nissila/33763460836/in/dateposted-public/What some photographers do is go higher up and shoot from the stairs with something like a 600mm f/4, to get clear ice as background. However, then you get the perspective of a higher vantage point which is not in my opinion as intimate as being at ice level. And having no audience in the background can be a bit boring as well. I think the 180-400/4 TC could be ideal for such shots other than the fact that there is one stop loss compared to the fast primes.
Here is a crop of a 300mm f/4 shot from 8th row (I don't remember specifics but ISO 6400, f/4 seems likely).
https://www.flickr.com/photos/ilkka_nissila/33803606665/in/dateposted-public/You can see that in the latter case there is no distraction in the background but I prefer the ice level intimacy and blurry blobs of spectators rather than the perspective of a distant observer. However, I grant that this perspective has its advantages.
Jeff Cable shot some figure skating with Canon's 200-400/4 Extender in Sochi Winter Olympics and posted some of them on his blog:
http://blog.jeffcable.com/2014/02/figure-skating-photos-from-team.htmlIn this case the rink boards were not covered with advertisements (apart from the event itself) and this must make the work of photographers a bit easier, though I don't think having the text SOCHI behind the atletes helps those images visually (the olympic rings are nice, though).
With wildlife photography, the only time I shoot f/2.8 is if I am using a 2x extender, which gives me an effective f/5.6.
You have a smaller subject than I do. And nature is a very different shooting environment than a stadium or arena where advertisements are purposefully placed to be difficult to avoid in television and photography coverage.