There are (small) differences in wheel and tire design to support the sealant based system, and that makes all the difference I guess. Slime tubes are pretty reviled, tubeless is the hot thing. Besides being more reliable it also allows for lower pressures, which is probably the main reason it has become popular. There is very little downside for riders (tubeless is just a bit slower than high end tubes that very few riders use), but for the home mechanic they’re a bit of a pain to work on.

No. I've been riding a road tubeless setup in Seattle and surrounding countryside for half a decade now and the feel has nothing to do with Slime. 55mm x ISO 559 lightweight road tires with Orange Seal. (In the NW we like wide road tires : )

Something like 10k miles later I've had zero incidents where I had to fix something on the road. You do have to more maintenance (e.g. make sure you have adequate sealant in the tires periodically) but for regular year round use especially, it is a worthwhile trade.

Not sure about road biking, but at least in the mountain and gravel communities it's almost universal. There are 3 popular sealant brands that I'm aware of: Stans, Orange Seal, and Slime.

I have been riding and racing bikes since 1990, and I think tubeless is one of the best real innovations. Fixing flats sucks.

Not sure if they still make them, but some many years ago I tried out some Slime tubes that had the stuff built into the tube somehow. Not only did it not work to seal punctures, it was impossible to patch.

I like the slime inner tubes. They've saved me a few times. Only on lowish pressure tyres though, I can't imagine they work well on a road bike.

People do get annoyed with tubeless to be honest. Its a mixed bag of people who like it because the rolling resistance is 1 watt lower, and people who hate it because its a lot more maintenance keeping up with sealant and hard to patch sometimes compared to just throwing in a new tube (which a lot of tubeless users end up doing when they get a puncture flat anyhow).