Because from like a 'tick off this list of engineering and science issues'-perspective, tokamaks (and arguably stellarators) are the furthest along. Alternative approaches pretty much all have a larger number and arguably less certain-to-succeed hurdles to overcome.
Yes, that would be my analysis. I would even call it cliche at this point. Every approach I am aware of has discovered challenges to confinement that were not obvious before experiments of sufficient scale were done. The only exceptions are approaches that have not been demonstrated at sufficient scale for these problems to be documented yet, and ill-advised inertial confinement concepts that cheat by relying on fission and don't scale well below multiple terajoules per shot.
That doesn't mean there's no possible confinement concept that has better scaling properties, different approaches having different scaling characteristics happens all the time in nature, but it does mean the technical risk of unproven concepts is extremely high and anticipating commercial viability for those before they're demonstrated seems premature.