I don't think any of us are saying that this always happens with high gravity beers. We're just saying that it can happen, and when it does you have a few options. You can open bottles and re-pitch, force carb individual bottles, or wait it out. For those of us that have chosen to wait it out, it can take a long while.
I've had this problem once in my brewing history, and it wasn't even high gravity. It was only a 6.5% beer. My theory was that the yeast I used was high flocculating yeast that had settled out to the point of there being very little left in suspension. On bottling day I likely racked very clear beer that had an extremely low cell count which caused an extremely slow carbonation process. The beer literally took over 10 months to carb, but it did eventually. Sure, I wasn't happy about the wait, but I had enough homebrew to keep my happy. Since then I always swish the racking cane in to the yeast cake to pick up a little yeast when racking to a bottle bucket to ensure I have a decent amount of yeast.
Of coarse the other possibility in some cases is that a person may have used a yeast that didn't have a high enough alcohol tolerance to handle the job of carbonating. In that case you can indeed re-pitch a different yeast in the bottle. In that case I would be careful not to pitch yeast that is going to massively attenuate and overcarb or dry out the beer. Maybe instead of champagne yeast I would consider using an ale yeast with a higher tolerance than the yeast used for fermentation, if at all possible.