No good if you get a cut rather than a pinhole puncture.
Same issue with a tubed tyre though, if you get that kind of puncture (rare) then yes you put a tube in, the point being that it IS rare, and for the 99% of the time you're riding without a tube you get the benefits of tubeless
So if you get a puncture when out for a ride how do you fix it
For most normal punctures* the sealant seals it before you notice, for bigger holes** it will often seal with a bit of sloshing around and then you just re-inflate (with a normal pump) and carry on.
For punctures that won't easily seal*** you use a tubeless tyre plug (AKA worm), this is done in-situ without removing the tyre and takes less time than patching a tube, you then re-inflate (with a normal pump) and carry on.
If it's a proper massive carcass tear**** then you boot it and bung a tube in.
The thing you have to remember is that even if you do have to put a tube in, that's no worse
than what you'd have to do with a tubed tyre, but it is/might be better for the rest of the time
, and it's also a rare occurrence.
You fill them full of sealant.....
not 'fill' but there is some sealant in there
How much does that weigh .... more than an inner tube ..... ?
no, much less, 60ml for up to ~2.2 MTB tyre, so that or less for road.
Really ....... Emperors New Clothes ....
This is marketing gibberish .... Just a personal thought .....
And breathe .....
Anyway, you don't have to do it, tubes aren't going anywhere, if you don't want any of the tubeless benefits or don;t think they will benefit you then it has literally no impact on you, but don't begrudge other people for taking advantage of them.
There are lots of 'questionable' technologies and things out there that have been pushed on the public, but that doesn't mean that they're all bogus, some have real benefits for a lot of people.
I've been fully tubeless for MTB and offroad for over a decade, wouldn't go back if you paid me, still not bothered on the road bikes though, due to a combination of being happy with the tyres and wheels that I have, and not really getting that many punctures anyway.
I think Brucey highlights the main road tubeless issue at the moment, which is lack of standardisation and variable tolerances. If everything was standardised and tolerances were good enough to mean that all combinations worked acceptably it'd be different, but there's too much variation at the moment. Doesn't mean it doesn't work, just that a the moment you are a little limited as you have to find (trial and error) a combo that does work for you, or go the safe option and go for an all matching 'system' and resulting lack of options/freedom.
On the MTB side things have got better on the standardisation front, I mean it's still not there fully but many more combinations are likely to work and it's pretty mainstream, certainly nearly everyone racing will be tubeless, and a lot of recreational riders swapped several years ago.
* I don't know how many times this has happened really as I don't notice when riding, I do notice the myriad of 'things' poking through the inside of my tyres that would have caused a puncture with a tube when I do eventually take them off though.
** maybe 3 or 4 times a year?
*** once or twice a year?
**** once every 2-3 years or so
^ that's all based on me riding my MTB every weekend, sometimes midweek too, and normally a full winter and summer season of racing.