How many people want or need F1.2? Even 1.4 on FF seems like a ridiculously narrow dof.
F2.8 is usually perfect for concerts, imho, since you're often looking up at the stage from an extreme angle if you have access to row zero, plus, you usually have spotlights to help out.
But that's the point I was making: F2.8 zooms (and now F2 and F1.8 zooms) and modern ISOs are so very good that if you're going to bother with a prime, it had better be able to do something completely alien or supernatural in nature. (Just like a camera needs to be a serious step up to bother with it over a cell phone.) It doesn't mean you ALWAYS have to shoot F1.2 but it needs to have the option, imho, if you're going to purchase it to begin with.
There are still people who preach in the "emotional purity" of primes (especially for "learners") or are anti-size people who must have the smallest gear at all times, but for most people, the time of primes seems to be over.
The Sigma 28-45 F1.8 has gotten a lot of hate from photographers ("I guess it's a reasonably sharp 35mm that gives you some wiggle room for framing") but they don't get it, imho: no matter what, you're
always zooming with your feet with that lens, the zoom isn't about zoom but about giving you 28mm for places and 45mm for faces. It's the two different compression effects for one lens and its a lesson you learn as soon as you start with video. And I do think that being forced to do that at least some times helps with your photography (it's helped with my narrative/storytelling for stills immensely).
I guess for dark events like concerts or dances without flash, where the alternative is the shot being too dark altogether?
Yeah, all the anti-noise software out there is REALLY good at taking the noise out of bokeh balls in bird photography (where you've obliterated the background) but it can often look actively bad, worse than raw noise, in "maybe you shouldn't have taken that shot at the party, at all" situations.
Non studio flash photography isn't really hot anymore, outside of people who sometimes try to recreate crappy American Apparel ads for Instagram occasionally. The times when you have the perfect room to bounce over your right shoulder into a nearby corner on a white wall are... lacking. Plus, if you're shooting video as well, you really can't have a bracket to rotate your flash since you often don't have access to your hotshoe with a full rig (OTOH, with modern resolutions, vertical crops from horizontal shots are often fine. Yet for that same reason you can often be further away from the subject and crop in, which gives you a more respectable depth of field even wide open.)
I'm
far from a flash expert but I recently had a step and repeat where I had a flash setup on a c-stand with a modifier and when there were a lot of people I still had them casting shadows on each other and I just got a better image dropping to F1.8 and 1/60 and hoping for the best with the flash turned off. But the extra stop of light that F1.2 would have given me could have given me a much cleaner image. And of course there's no flash for video (hence me salivating a bit about what the Sigma 28-45 could do for my 120FPS basketball footage where I could cut my ISO by 1/3rd or by half in a lot of gyms!)
Most of the time, these days though, I'll just bring a pair of 24" tube lights and some Amazon Basics style stands to events and set up an informal step and repeat, if there isn't an official one, because they help out not just me but
everyone trying to take pictures with their phones as well. People get a lot of pleasure out of taking and posting their own stuff, not waiting around for the official pro shot, anyway, so it's best to help out as many people as possible since I have the gear and it's so easy to pack and set up.