And there will be just as many people, or more, who will state that the externally applied repair kept the leak sealed for the remainder of the life of the tire with no further intervention.
That's the fun part of anecdotal evidence, it's worth what we pay for it.
Yes, but I have never ever seen properly applied vulcanizing patch fail and I've been patching tyres for 40-yrs. On autos too. Must be close to thousand by now. I've had plenty of my own and other's plugs fail. I always yank on them hard before riding off. Sure, good plug with vulcanizing fluid can last rest of tyre's life, but overall failure rate is still higher than proper patches on inside. Partly because there's so many crappy plug kits out there with poor glues.
In early days, yes I had patches not work on bicycle tubes when I was learning during my paper-boy years. Prep is most important part, have to sand off mould-release layer on inside of tyre. And use proper vulcanizing patch with uncured rubber. There's difference between Rema TipTop vs. Camel patches. That's why so many plugs and worms fail, they don't fully bond to inside of tyre. And rubber-cement is NOT same as vulcanizing fluid. It doesn't have ethylcyclohexylamine which generates poly-vinyl cross-linking with sulfur.
There's this thing known as stress-riser and engineers spend lots of time designing parts so that loads are transferred along part cleanly. I've tracked and raced plenty of patched tyres until they're fully worn. I would certainly
not do that on plugged tyre because you damage lots of casing cords from using reamer.
There's lots of mis-labeling of parts, probably due to some translation issues were "rubber cement" is used in cases where it really is "vulcanizing fluid". In most cases however, "rubber cement" really is rubber cement like we used in kindergarten. Without sending off for chemical analysis, you can drip drop onto glass table and see how it dries. Vulcanizing fluid has ethylcyclohexylamine catalyst that activates sulfur and not a glue-layer. So when it dries, there's nothing left. Rubber cement dries into rubber ball.
Rubber cement is a glue, that's what holds 2-layers of paper together. And it's a weak glue. Try applying non-sulfur patch (all black) with rubber cement and you'll be able to peel patch off later. A vulcanized patch has bonds across joint and both layers are fused together. You'll end up tearing patch and tyre trying to separate them.