Nope, it's easy to carry spare inner tubes, and everyone has them. A tubeless sealant failure wouldn't be so easy.
In 800 km of audaxes, no punctures. But my crankset did eat the chain at kilometre 10 of last year's Moonraker's and Sunseekers... a helpful passer by in Bath helped me fix that, but the damn thing was skipping a bit for the next 310 kms!
I ride audax and have used nothing but tubeless for six years and a little over 50,000 km. I do carry a tubeless repair kit ('worms', glue, worm poking tool), a tube, levers, a tyre boot and a pump, though I've never used any of these things on the road. I do pay close attention to tyre condition.
I have a new bike coming and plan on much longer rides. It’s fitted with Schwalbe pro ones and I specced tubeless. To be honest I cannot think of why I did or if it’s a benefit. I happily change tyres and tubes an don’t suffer any punctures really. Interesting to read Audaxes comments regarding them.
Thanks so far to all