SAC hasn't really made sense for the more modest channel counts for quite some time now. I would say as soon as the X32 came out and the lower end Soundcrafts and Allen and Heaths it was pretty pointless to go with SAC if you needed 24 inputs or less and didn't need a ton of outputs either. Almost all of these are easier to use, they start right up with the flip of a switch as soon as you take them out of the box, etc, etc, etc....
Heck even the Presonus desks were a better choice for some users and those have been around for quite some time now. Although I personally would have taken a 01V96 over that crap any day, those desks were not very live sound friendly... you actually had to think about how you would use them live.
SAC or the computer mixing thing in general really only makes a lot of sense when you need to mix a large channel count and/or you want a lot of routing flexibility (since AMP and SAC have a ton more bus and other routing options than most , if not all, of the under $5K desks do) and you don't have the funds to spend on one of the big boy Digicos or LCS or Digidesign, etc... Or if you just really like to tinker with computers and it's as much of a hobby as it is a job then have at it...
But lets be real, I would bet the majority of SAC users probably didn't even spend that much on their systems. I think most took some computer parts they already had around, eBay shopped for deals on sound cards, preamps, etc... and built themselves a fairly decent set up for probably only a little bit more than that $3000 price tag. I know I've spent quite a bit more than that, but I actually own enough MOTU and Preamps and computers and just about all the parts needed to have two simultaneous 72 input by quite a few output SAC or AMP rigs. I don't actually have the licenses for all that, and most of that gear is because I use my production computers for a lot more than just audio mixing. They just usually have a more modest I/O count. I also did that so I had to install and remove less gear from theatres when there was no shows.