To maximize the advantage of a tubeless, many users inject a sealant so minor punctures essentially go unnoticed. If you get a bigger puncture that the sealant can't handle, then you get to put a tube into a slimy tire and later patch the tire and deal with a slimy tube.

If no sealant is used, then a tube in installed just like any other clincher. The tire still needs to be patched at some point.

Mounting and getting the tire to seat upon initial istallation is sometimes a hassle. It can take a big shot of air to push the tire out so it seals.

I agree about the tubular hassle. I would never want to carry a bulky preglued spare.

I've gone as long as three years without a single puncture, but most often have 2-4 per year. Last year I had 10, including one that slashed a tire so badly that I was lucky to be able to boot it and get home. If I'd been riding tubulars, the cost of all the repairs would have been huge. I consider tubulars to be race day items and I don't race.