Shouts on Bahamut can be spotty, but they definitely exist (especially when a certain someone is currently subscribed). And I've seen them for just about everything up to V15 clears, and I'm aware of a few V15s people got through shout groups, although the harder the content, the rarer the shouts are obviously. There's very little consistency though. You can go all month without seeing an Omen shout, and then suddenly some rando guy will start shouting for a couple weeks or something. About 50/50 chance some Sortie group needs a fill on any given night and resorts to shouts, usually at least 4-6Bosses. We had a good string of Segment shouts around the Holidays, even some RP farms popping around that time, but those have dried up a little bit. Quite a bit of grouping actually happens in Discords these days too, I see at least a couple Sortie groups I know of that will try to find reps in Discords before resorting to shouts, so even if you're not in a static, having the LSs discords can be an advantage (assuming you don't mind being in a dozen+ XI related discords).
All that said, obviously you'll get more activity in a LS, and a decent number of shells on the Concierge that openly recruit run things like Divergence, Omen, and even some Odyssey.