I've had no leaks in my HTT, and I've had it for some years now (bought it new) and store it outside uncovered. It's seen everything that the weather here has to offer (which is quite a lot).
I suspect MOST people don't have leaks (although there's no way to definitively know this) but when someone does, they seek help - by coming here and posting about it. i.e. The posts here don't necessarily represent a fair sampling of the larger population of HTT owners.
That said, any trailer from any brand, can have a leak at some point. If buying used, be sure to inspect it very carefully before buying.
11' of blowing rain ...
Okay, now there's something my trailer hasn't been through. 11 feet is A LOT of rain! :)