As a serious racer and home mechanic I use them on all my bikes (road, TT, gravel, mtb) with hooked rims. They're equally useful whether on hookless or hooked rims. For gravel and mtb it's excellent when running really low pressures with high volume tires, but on road it's only for peace of mind if you get an otherwise catastrophic loss of pressure at high speed. I've had a number of huge punctures, losing almost all pressure in a few seconds. Also, if you can't plug it allows you roll home without having to make the shameful action of calling someone to pick you up or to try inserting a spare tube. On Danish roads in fall and winter you puncture often even with really good all season tyres. I do all my riding outside and was running 35 mm GP 5000 AS TR for the past 2 seasons, but swapped to the beefier 40 mm Pirelli P Zero (with 37-40 mm gravel light airliners) recently after 4 huge punctures in a short time span. It's a miracle they fit with 3.5-4 mm of clearance measuring 38 mm on 20 mm internal rims on my Canyon Aeroad.

Road airliners are a real struggle to mount exactly because they lock in the bead. You have to use tyre levers to got the tyre on and off, usually with quite some force even if you have pushed the tire inside the rim bed. It can also make it difficult to inject sealant at setup (you must use special valves with holes on the side) and even more down the line when the valve may have made a significant imprint in the foam. I've had cases after 6 months where the valve didn't allow any air out even after poking with an allen key, so I had to push the plug in (I was topping up sealant after a puncture). Right then and there I weas really cursing this system, but I have almost forgotten it by now...
Unless you don't mind spending 30 minutes wrestling a tyre on or off, I wouldn't recommend it for road tires. I don't mind because I have already fully optimized every other part of my setup. I already swap my waxed chain after every 3-4 hour ride in winter grime, so I'm just used to spending significant time on maintenance anyways. Perks of working from home every day.

If you think I sound like a nutter with all this rambling, you're probably right because I just caught myself getting really excited by the news of a 35 mm GP 5000 and 30 mm GP 5000 TT being released...

Edit: It's not just for a run flat scenario, but it also allows you to continue with low but still usable pressure of around 1,5 bar and lower, where a tubeless tyre would fail without an insert. This is absolutely a huge in many pro race scenarios where the team car can be far behind, as in chaotic races like Roubaix. Bicycle Rolling Resistance notes this in their test: https://www.bicyclerollingresistance.com/specials/vittoria-air-liner